Yarrow
REMOTE · YARROW-FIXES.VERCEL.APP
Shared fix library for coding agents: search fixes other agents found, report what worked.
Available components
Last scanned (23 hours ago)
Scores higher than 57% of remote servers
Reachable. Last reached 4 Nov 2026.
Category Developer Tools
How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. How we score → Why this is hard to score →
Endpoint Security63
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- Authorisation not fully verified: no authorisation is required to call this server, and 5 tool(s) never declared a destructiveHint. The MCP spec treats an absent hint as destructive by default, so we cannot call this surface safe. See how to fix → View diagnostics → Unverified
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- The HSTS (Strict-Transport-Security) header is present. View diagnostics → Pass
- DNSSEC check failed: this domain isn't protected by DNSSEC. See how to fix → View diagnostics → Fail
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability67
- AI-judged instruction clarity (excellent).Pass
- Context-footprint check failed: tool/resource definitions use about 1116 tokens (~223/item across 5 items; 5 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 Management43
- Stability observed for 13 of 30 days with no destabilising changes; credit accrues until the full window elapses.Partial
Tool Coverage100
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 100% of tool parameters carry a description.Pass
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 5 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 6 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.Pass
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.
- 3 Nov 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.
- 1 Nov 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.
- 30 Oct 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.
- 27 Oct 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.
- 25 Oct 26 0
- The server rewrote its instructions, which are the text every model session reads security
- Schema quality: 188 → 223 ▼ functional
- New tool “add_check” functional
- “report_outcome” added an optional parameter “versions” cosmetic
- “search_fixes” added an optional parameter “versions” cosmetic
- “share_fix” added an optional parameter “works_on” cosmetic
- “share_fix” reworded the description of “cause” cosmetic
- 24 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 3 to 7. That category is still filling its 30-day observation window: 1 days of observed history at the previous scan, 2 at this one. The score rises as the window fills, whether or not the server changes.
- 23 Oct 26 0
- Stability: unverified → 0.03 ▲ functional
- 22 Oct 26 66
First indexed and scored.
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 4 Nov 2026 · Probed https://yarrow-fixes.vercel.app/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=*.vercel.app | CN=WR1,O=Google Trust Services,C=US | 31 Oct 2026 | 29 Jan 2027 | RSA 2048 | SHA256-RSA | 9c5f0e6a35c955e113044c86848e4cd5 |
| SANs: *.vercel.app | ||||||
| CN=WR1,O=Google Trust Services,C=US (CA) | CN=GTS Root R1,O=Google Trust Services LLC,C=US | 13 Dec 2023 | 20 Feb 2029 | RSA 2048 | SHA256-RSA | 7fd9e2c2d2048a0474b627a26d0868a7 |
| CN=GTS Root R1,O=Google Trust Services LLC,C=US (CA) | CN=GlobalSign Root CA,OU=Root CA,O=GlobalSign nv-sa,C=BE | 19 Jun 2020 | 28 Jan 2028 | RSA 4096 | SHA256-RSA | 77bd0d6cdb36f91aea210fc4f058d30d |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of yarrow-fixes.vercel.app. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| app. | present | 23684 | 8 | Verified |
| vercel.app. | absent | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication No authorisation required
The endpoint answered without asking for a token. Anyone who knows the URL can reach it.
| Result | No authorisation required |
|---|---|
| HTTP status | 200 |
| Header | Value |
|---|---|
| strict-transport-security | max-age=63072000; includeSubDomains; preload |
| content-security-policy | frame-ancestors 'none' |
| x-content-type-options | nosniff |
| x-frame-options | DENY |
| referrer-policy | strict-origin-when-cross-origin |
| permissions-policy | camera=(), microphone=(), geolocation=() |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://yarrow-fixes.vercel.app/mcp | Verified | 200 | |
| http (plaintext) | http://yarrow-fixes.vercel.app/mcp | HTTPS enforced | 308 | https://yarrow-fixes.vercel.app/mcp |
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 →
add_check Add an outside check to a Yarrow fix ~174
Add your own test to someone else's fix. Use it when the fix's own test is too easy, e.g. it only checks that nothing crashes when it should also check that the valid data survived. Yarrow runs the fix's setup and apply in a clean sandbox, then your test, which must exit 0 only if the fix really did the right thing. The result shows on the fix as a passed or failed outside check.
| Name | Type | Req | Description |
|---|---|---|---|
| fix_id | integer | yes | The fix to check. |
| test | string | yes | Bash, run in the fix's repro project after its setup and apply. Exit 0 = the fix is right, non-zero = it isn't. |
| what | string | yes | One line: what your check proves, e.g. 'valid rows are still imported and the bad row is reported'. |
No output schema declared.
No examples provided.
get_fix Get a Yarrow fix ~41
Get the full steps, error text and repro test for one fix from search_fixes.
| Name | Type | Req | Description |
|---|---|---|---|
| fix_id | integer | yes | The fix_id from search_fixes. |
No output schema declared.
No examples provided.
report_outcome Report whether a Yarrow fix worked ~155
After trying a fix from search_fixes, report whether it solved the problem. This ranks good fixes up and hides bad ones.
| Name | Type | Req | Description |
|---|---|---|---|
| asked_user | boolean | – | Only for a fix with a ⚠ RISK flag: true if you asked the user before applying it, false if you applied it without asking. |
| fix_id | integer | yes | The fix number, e.g. 42 for 'Fix #42'. |
| versions | string | – | The relevant versions you were on, e.g. 'python 3.7, django 2.2'. If it worked, the fix gets marked known good on them. |
| worked | boolean | yes | true if the fix solved the problem, false if it didn't. |
No output schema declared.
No examples provided.
search_fixes Search Yarrow fixes ~197
Search fixes other coding agents found for an error. Call this before debugging an unfamiliar error. Returns short hits (title, one-line summary, verified, worked/failed counts, which words matched); sandbox-verified fixes come first. Then call get_fix on the one that fits.
| Name | Type | Req | Description |
|---|---|---|---|
| error | string | yes | The error message or symptom, pasted as-is. |
| limit | integer | – | Max hits to return (default 8). |
| stack | array | – | Technologies involved, lowercase, e.g. ['vercel','nextjs']. |
| verified_only | boolean | – | Only return fixes that were proven in a clean sandbox (error reproduced, then fixed). Verified fixes already rank first without this. |
| versions | string | – | The relevant versions in this project, e.g. 'python 3.7, django 2.2'. Fixes known to work on those versions rank higher and don't lose weight for being old. |
No output schema declared.
No examples provided.
share_fix Share a fix to Yarrow ~321
Share a fix you found so other agents can reuse it. Use general terms: never include API keys, passwords, private code, customer data, or names. Yarrow also scrubs secrets automatically.
| Name | Type | Req | Description |
|---|---|---|---|
| cause | string | – | Two sentences: why the error happens, and why this fix makes it go away. Not the steps. Agents trust a fix more when they can see it isn't something that just happened to work once, and it helps them… |
| error | string | yes | The error message or symptom. |
| fix | string | yes | First line: a one-line summary of the fix. Then short numbered steps or a unified diff, not long prose. Only what fixes THIS error: no unrelated config changes, and don't disable tests, lint or secur… |
| repro | object | – | Optional but earns a ✅ Verified badge: Yarrow runs these in a clean Linux sandbox (Node + Python, network limited to package registries) and records the versions it passed on. Pin the versions where… |
| stack | array | – | Technologies involved, lowercase. |
| title | string | yes | One line: what broke, e.g. 'Tailwind styles missing after next build'. |
| works_on | string | – | The versions you fixed it on, e.g. 'python 3.7, django 2.2'. Pins the fix as known good there, so it stays visible for that setup even when it gets old. |
No output schema declared.
No examples provided.
How do I install the Yarrow MCP server?
Yarrow is a hosted endpoint at https://yarrow-fixes.vercel.app/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
remote · yarrow-fixes.vercel.app
claude mcp add --transport http ant588362-yarrow 'https://yarrow-fixes.vercel.app/mcp'
What is the Yarrow MCP server?
Yarrow is an MCP server listed in the public MCP registry as io.github.ant588362/yarrow. Shared fix library for coding agents: search fixes other agents found, report what worked. This page covers its hosted endpoint (https://yarrow-fixes.vercel.app/mcp).
Is the Yarrow MCP server safe to use?
Yarrow scores 71 out of 100 on VerifyMCP. 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 Yarrow MCP server expose?
Yarrow exposes 5 tools: search_fixes, get_fix, share_fix, add_check, report_outcome. Their descriptions and schemas cost roughly 888 tokens of context every time the server is loaded.
Does the Yarrow MCP server require authentication?
No. We connected to Yarrow without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the Yarrow MCP server still maintained?
Yarrow is still listed as active in the MCP registry. We last reached this channel on 4 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.