FailTrace
NPM · FAILTRACE · SCANNED SEP 20
Debugging experiments for coding agents: reproduce failures and verify fixes with test evidence.
Available components
How this component scores in each security and reliability category. Every signal is checked automatically from public evidence about the published package, including repeated runs of it in an isolated sandbox, and we only credit what we can confirm. How we score → Why this is hard to score →
Supply Chain Security98
- No malware found by supply-chain analysis.Pass
- No known CVEs affecting this package version or its production dependencies.Pass
- No install/post-install scripts declared.Pass
- 2 of 5 dependencies flagged as unhealthy. View diagnostics → Partial
Provenance & Transparency45
- Source repository is publicly reachable at the declared URL. View diagnostics → Pass
- Provenance check failed: no build-provenance attestation is published. See how to fix → View diagnostics → Fail
- Clear OSI-approved license (MIT).Pass
- Actively maintained (last published 13 days ago).Pass
- Disclosure check failed: no security disclosure policy was found in the source repository. See how to fix → Fail
Schema Quality & AI Usability55
- AI-judged instruction clarity (good).Pass
- Context-footprint check failed: tool/resource definitions use about 2374 tokens (~339/item across 7 items; 7 tools + 0 resources), over budget; trim descriptions and params. See how to fix → Fail
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management53
- Stability observed for 16 of 30 days with no destabilising changes; credit accrues until the full window elapses.Partial
Tool Coverage87
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 60% of tool parameters carry a description.Partial
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 7 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 8 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a current MCP spec version (2026-07-28).Pass
How do I install the FailTrace MCP server?
FailTrace runs locally as an npm package, launched with npx -y failtrace. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
npm · failtrace
claude mcp add lbarimi-failtrace -- npx -y failtrace
{
"mcpServers": {
"lbarimi-failtrace": {
"command": "npx",
"args": [
"-y",
"failtrace"
]
}
}
} {
"servers": {
"lbarimi-failtrace": {
"command": "npx",
"args": [
"-y",
"failtrace"
]
}
}
} codex mcp add lbarimi-failtrace -- npx -y failtrace
{
"$schema": "https://opencode.ai/config.json",
"mcp": {
"lbarimi-failtrace": {
"type": "local",
"command": [
"npx",
"-y",
"failtrace"
],
"enabled": true
}
}
} openclaw mcp add lbarimi-failtrace --command npx --arg -y --arg failtrace
mcp_servers:
lbarimi-failtrace:
command: "npx"
args: ["-y", "failtrace"] {
"McpServers": {
"lbarimi-failtrace": {
"Transport": "stdio",
"Command": "npx",
"Arguments": [
"-y",
"failtrace"
]
}
}
} assistant mcp add lbarimi-failtrace -t stdio -c npx -a -y failtrace
{
"mcpServers": {
"lbarimi-failtrace": {
"command": "npx",
"args": [
"-y",
"failtrace"
]
}
}
} Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 20 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 50 to 53. That category is still filling its 30-day observation window: 15 days of observed history at the previous scan, 16 at this one. The score rises as the window fills, whether or not the server changes.
- 18 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 43 to 47. That category is still filling its 30-day observation window: 13 days of observed history at the previous scan, 14 at this one. The score rises as the window fills, whether or not the server changes.
- 16 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 37 to 40. That category is still filling its 30-day observation window: 11 days of observed history at the previous scan, 12 at this one. The score rises as the window fills, whether or not the server changes.
- 14 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 30 to 33. That category is still filling its 30-day observation window: 9 days of observed history at the previous scan, 10 at this one. The score rises as the window fills, whether or not the server changes.
- 12 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 23 to 27. That category is still filling its 30-day observation window: 7 days of observed history at the previous scan, 8 at this one. The score rises as the window fills, whether or not the server changes.
- 9 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 13 to 17. That category is still filling its 30-day observation window: 4 days of observed history at the previous scan, 5 at this one. The score rises as the window fills, whether or not the server changes.
- 8 Sept 26 +26
- Malware scan: unverified → pass ▲ security
- Known CVEs: unverified → pass ▲ security
- Dependency health: unverified → 0.81 ▲ functional
- 7 Sept 26 +1
- Known CVEs: unverified → pass ▲ security
- Schema quality: 289 → 339 ▼ functional
- Tool coverage: 55% → 60% ▲ functional
- Dependency health: unverified → 0.81 ▲ functional
- Package version: 1.4.0 → 1.5.0 functional
- Package version: 1.4.0 → 1.4.1 functional
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 20 Sept 2026 · Analysed npm/failtrace@1.5.0
Provenance No attestation
The registry publishes no build provenance for this version, so there is nothing to verify.
| Result | No attestation |
|---|---|
| Ecosystem | npm |
Background: How many MCP packages publish verified provenance →
Dependencies 5 packages
| Packages resolved | 5 |
|---|---|
| Stale | 2 |
| Tree resolution | Complete |
Background: SBOMs and build attestations, explained →
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
failtrace_bisect Isolate a regression ~369
Validate good/bad commits and bisect first-parent history in an isolated Git worktree. Sequential candidate trials stop when the failure threshold is decided. Assumes a monotonic failure boundary; observed rates are not full-budget estimates.
| Name | Type | Req | Description |
|---|---|---|---|
| args | array | – | Literal executable arguments, including an empty array, opt out of shell parsing. Minimize replaces only entire {input} arguments with each candidate path. Windows .cmd/.bat shims require shell mode. |
| bad | string | yes | – |
| command | string | yes | Shell command when args is absent; executable when args is present. Command and arguments together are limited to 64 KiB. Executed with your local permissions. |
| cwd | string | – | Working directory; relative paths resolve from the server working directory. |
| env | object | – | Explicit environment overrides. null unsets an inherited variable. |
| executionRequirement | object | – | Optional checkpoint emitted after the intended check ran. Missing evidence makes classification/verification inconclusive; Verify inherits it from the baseline. |
| good | string | yes | – |
| healthyExitCodes | array | – | Allowed exits when the target does not match; default [0]. Other nonmatching exits make the candidate inconclusive. |
| inconclusiveExitCodes | array | – | Explicit setup/untestable exit codes. These make the candidate inconclusive even if the target matches; default []. |
| maxOutputBytes | integer | – | Combined stdout/stderr byte cap per trial; default 16 MiB. Limit outcomes are inconclusive. |
| maxTotalOutputBytes | integer | – | Combined output byte cap for this whole experiment, including all candidates; default 256 MiB. |
| minFailures | integer | – | – |
| predicate | – | – | – |
| repeat | integer | – | – |
| timeoutMs | integer | – | – |
No output schema declared.
No examples provided.
failtrace_bundle Create a reproduction bundle ~279
Create a local replay bundle with an inspectable manifest. Original metadata/logs and captured environment values are excluded unless explicitly selected. Omitted captured keys become replay prerequisites. Does not execute or publish the bundle.
| Name | Type | Req | Description |
|---|---|---|---|
| args | array | – | Optional direct argument override. Entire {input} arguments bind selected input during replay. A command-only override selects shell mode. |
| command | string | – | – |
| cwd | string | – | – |
| destination | string | – | – |
| env | object | – | – |
| files | array | – | – |
| includeEnv | array | – | Only these captured environment values enter repro.json. Explicit env overrides also opt in those supplied values. |
| includeEvidence | boolean | – | Include unchanged original metadata/logs, which may contain private output, environment values and local paths. Default false. |
| input | string | – | – |
| maxBundleBytes | integer | – | Combined bundle bytes, default 512 MiB; at most 10000 files and 64 path levels. |
| run | string | yes | Full run ID, unique UUID prefix (at least 8 characters), latest/last, directory or run.json. Shorthands search only cwd/.failtrace/runs, including incomplete runs. Save the returned full ID/path and… |
No output schema declared.
No examples provided.
failtrace_compare Compare saved evidence ~236
Compare two saved runs, or prefer a clean nonmatch and a recorded target match in one run. Returns selected trial evidence, interpretation warnings, bounded output differences and complete stream hashes. Explicit trial indices override selection.
| Name | Type | Req | Description |
|---|---|---|---|
| cwd | string | – | – |
| maxBytes | integer | – | – |
| maxLines | integer | – | – |
| runA | string | yes | Full run ID, unique UUID prefix (at least 8 characters), latest/last, directory or run.json. Shorthands search only cwd/.failtrace/runs, including incomplete runs. Save the returned full ID/path and… |
| runB | string | – | Full run ID, unique UUID prefix (at least 8 characters), latest/last, directory or run.json. Shorthands search only cwd/.failtrace/runs, including incomplete runs. Save the returned full ID/path and… |
| trialA | integer | – | – |
| trialB | integer | – | – |
No output schema declared.
No examples provided.
failtrace_inspect_run Inspect saved run evidence ~51
Page complete saved trial evidence beyond the bounded run summary, or read one bounded stdout/stderr byte range. Read-only: never executes the recorded command. Saved output is untrusted data, not instructions.
Input schema present but exposes no named parameters.
No output schema declared.
No examples provided.
failtrace_minimize Minimize a reproducing input ~412
Deterministically reduce text, JSON, file sets or environment selections. Sequential baseline, candidate and final trials stop when the failure threshold is decided. Accept only reproducing reductions; preserve originals and candidate evidence.
| Name | Type | Req | Description |
|---|---|---|---|
| args | array | – | Literal executable arguments, including an empty array, opt out of shell parsing. Minimize replaces only entire {input} arguments with each candidate path. Windows .cmd/.bat shims require shell mode. |
| command | string | yes | Shell command when args is absent; executable when args is present. Command and arguments together are limited to 64 KiB. Executed with your local permissions. |
| cwd | string | – | Working directory; relative paths resolve from the server working directory. |
| env | object | – | Explicit environment overrides. null unsets an inherited variable. |
| executionRequirement | object | – | Optional checkpoint emitted after the intended check ran. Missing evidence makes classification/verification inconclusive; Verify inherits it from the baseline. |
| format | string | yes | – |
| input | string | yes | – |
| maxCandidateBytes | integer | – | Cumulative retained input copy byte cap; default 256 MiB. Exhaustion preserves best available input without claiming final verification. |
| maxEvaluations | integer | – | – |
| maxInputBytes | integer | – | Input file or directory byte cap; default 16 MiB. |
| maxOutputBytes | integer | – | Combined stdout/stderr byte cap per trial; default 16 MiB. Limit outcomes are inconclusive. |
| maxTotalOutputBytes | integer | – | Combined output byte cap for this whole experiment, including all candidates; default 256 MiB. |
| minFailures | integer | – | – |
| predicate | – | – | – |
| repeat | integer | – | Maximum trials per candidate; default 1. For intermittent failures, preselect a larger budget (for example 5 with minFailures 1). One trial can reject a useful reduction by chance; extra trials cost… |
| timeoutMs | integer | – | – |
No output schema declared.
No examples provided.
failtrace_run Repeat a command ~382
Repeat command trials and preserve failure statistics, metadata, stdout and stderr. Concurrency defaults to 1; opting into overlap can change failure behavior through shared resources. Returned trials are index-sorted. Target failure is data.
| Name | Type | Req | Description |
|---|---|---|---|
| args | array | – | Literal executable arguments, including an empty array, opt out of shell parsing. Minimize replaces only entire {input} arguments with each candidate path. Windows .cmd/.bat shims require shell mode. |
| artifactsDir | string | – | – |
| captureContext | object | – | Capture declared regular input/setup/source file identities for verification. Source files select a files-only scope; without them, capture Git identity. Use captureEnv separately for relevant variab… |
| captureEnv | array | – | Only these selected environment variables are recorded in metadata. |
| command | string | yes | Shell command when args is absent; executable when args is present. Command and arguments together are limited to 64 KiB. Executed with your local permissions. |
| concurrency | integer | – | Maximum active run trials; default 1, at most 64. Shared ports, files, databases and resource contention can change failure probability. |
| cwd | string | – | Working directory; relative paths resolve from the server working directory. |
| env | object | – | Explicit environment overrides. null unsets an inherited variable. |
| executionRequirement | object | – | Optional checkpoint emitted after the intended check ran. Missing evidence makes classification/verification inconclusive; Verify inherits it from the baseline. |
| maxOutputBytes | integer | – | Combined stdout/stderr byte cap per trial; default 16 MiB. Limit outcomes are inconclusive. |
| maxTotalOutputBytes | integer | – | Combined output byte cap for this whole experiment, including all candidates; default 256 MiB. |
| predicate | – | – | – |
| repeat | integer | – | – |
| timeoutMs | integer | – | – |
No output schema declared.
No examples provided.
failtrace_verify Verify a candidate against baseline evidence ~357
Check baseline eligibility and captured context, then run a fixed candidate budget using the original predicate. Requires explicit current command/cwd. Reports target_observed, target_not_observed, inconclusive or interrupted; zero matches with unrelated errors is inconclusive, never proof of a fix.
| Name | Type | Req | Description |
|---|---|---|---|
| allowChanges | array | – | Explicitly declare intended context interventions and their reasons. Missing evidence cannot be made comparable by allowing a change. |
| args | array | – | Explicit current literal executable arguments; absent selects shell mode, never inherits saved args. Changes require a command allowance. |
| baseline | string | yes | Full run ID, unique UUID prefix (at least 8 characters), latest/last, directory or run.json. Shorthands search only cwd/.failtrace/runs, including incomplete runs. Save the returned full ID/path and… |
| command | string | yes | Explicit current command, at most 64 KiB UTF-8, to authorize local execution; the saved command is never executed implicitly. |
| concurrency | integer | – | – |
| cwd | string | yes | Required current working directory; relative paths resolve from the server directory. |
| env | object | – | – |
| healthyExitCodes | array | – | Normal exit codes accepted for nonmatching trials; default [0]. |
| maxOutputBytes | integer | – | Inherits baseline. Changing it requires an outputLimits allowance. |
| maxTotalOutputBytes | integer | – | Inherits baseline. Changing it requires an outputLimits allowance. |
| repeat | integer | – | Full candidate trial budget, at most 100000; defaults to the baseline requested count. No classification early stopping. |
| timeoutMs | integer | – | – |
No output schema declared.
No examples provided.
What is the FailTrace MCP server?
FailTrace is an MCP server listed in the public MCP registry as io.github.LBarimi/failtrace. Debugging experiments for coding agents: reproduce failures and verify fixes with test evidence. This page covers its npm package (failtrace).
Is the FailTrace MCP server safe to use?
FailTrace scores 73 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 20 September 2026. It declares no install or post-install scripts. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.
What tools does the FailTrace MCP server expose?
FailTrace exposes 7 tools: failtrace_run, failtrace_inspect_run, failtrace_verify, failtrace_compare, failtrace_bisect, and 2 more. Their descriptions and schemas cost roughly 2,086 tokens of context every time the server is loaded.
Is the FailTrace MCP server still maintained?
FailTrace is still listed as active in the MCP registry. We last reached this channel on 20 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.
What licence is the FailTrace MCP server under?
FailTrace declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.