OPA MCP

Download Rego policies from an OCI registry or Git repository into a local directory using `conftest pull`. Use this to hydrate a local `policy/` directory before running `conftest_test`. Requires `conftest` on PATH or `CONFTEST_BINARY` set. The `policy` directory must be inside OPA_MCP_ALLOWED_PATHS. SECURITY: pulled policies are arbitrary Rego source that will be executed by `conftest_test`. Only pull from registries or repositories you own or explicitly trust -- malicious policy code can use OPA built-ins (http.send, opa.runtime) to exfiltrate data or make outbound network requests when the tests run.

Package the local Rego policy directory as an OCI artifact and push it to a registry using `conftest push`. Registry credentials must be pre-configured in the host environment (docker login, ORAS keychain, etc.) -- this tool never handles credentials. The `policy` directory must be inside OPA_MCP_ALLOWED_PATHS. Requires `conftest` on PATH or `CONFTEST_BINARY` set.

Evaluate configuration files (Kubernetes manifests, Terraform plans, Dockerfiles, Helm charts, or any YAML/JSON/HCL/TOML/INI) against Rego policies using `conftest test`. Returns per-file, per-namespace pass/fail/warn results so you can pinpoint exactly which policy rules fired. Requires `conftest` on PATH or `CONFTEST_BINARY` set; returns CONFTEST_NOT_FOUND otherwise. Provide config via `files` (disk paths) or `inlineConfig` (inline string). Provide policy via `policy` (disk path) or `inlinePolicy` (inline Rego source). Omit `policy` and `inlinePolicy` to use conftest's default `./policy` directory.

Run the `test_*` rules inside `*_test.rego` files within a conftest policy directory, verifying that the policies themselves are correct. Equivalent to `opa test` but using conftest's policy-loading machinery. Returns per-file pass/fail results. Requires `conftest` on PATH or `CONFTEST_BINARY` set; returns CONFTEST_NOT_FOUND otherwise.

Return the name, version, and runtime details of this opa-mcp server instance. Use this when you need to confirm which version of opa-mcp is running, or to verify that the OPA, Regal, and Conftest binaries are reachable.

Build a deployable bundle from policy / data paths using `opa build`. Output is a `.tar.gz` archive with optional inline signing. Supports optimization, custom revision strings, and the WASM target.

Sign an OPA bundle with a private key using `opa sign`. Writes a `.signatures.json` next to the bundle directory, or updates the archive in place.

Verify the cryptographic signature of a signed OPA bundle using `opa eval --bundle --verification-key`. The bundle must have been signed with `opa sign` (or `opa_bundle_sign`). OPA checks the `.signatures.json` manifest inside the bundle against the provided public key before loading any policy -- a tampered or unsigned bundle will fail with `INVALID_BUNDLE`. Returns `{ bundle, verified: true }` on success.

Send a query to the OPA server's `/v1/compile` endpoint for partial evaluation. Returns the residual query -- what remains after substituting in everything that's known.

Return the running OPA server configuration (sanitized -- secrets are not included).

Remove a document from OPA's data store at the given path. The path may be in dotted form (`users.alice`) or slash form (`users/alice`). OPA responds with 204 No Content on success; if no document exists at the path, OPA returns 404 which is mapped to `DATA_NOT_FOUND`. Root-path deletion (`/v1/data/` itself) is intentionally excluded -- supply at least one path segment.

Delete a policy by ID from the running OPA server.

Evaluate a policy decision against one or more input files using `opa exec --format=json`. Unlike `rego_eval` (single input), `opa exec` processes every file independently and returns a per-file result -- ideal for CI pipelines that check many config files against a policy in one call. Supply `bundle` for bundle-based policies or `dataPaths` for raw policy files; these are mutually exclusive. Each file that fails evaluation appears in `results` with an `error` field rather than a `result` field. Set one of `fail`/`failDefined`/`failNonEmpty` to turn the call into a CI gate: the result then reports `failed: true` (instead of erroring) when the gate condition is met.

Read a path from OPA's data hierarchy. The `path` argument may be in dotted form (`users.alice`) or slash form (`users/alice`).

Fetch a single policy by ID from the running OPA server.

Hit the OPA `/health` endpoint. Returns `{ healthy: true }` on 200. Supports `bundles` and `plugins` query flags to require those subsystems to also be healthy.

List policies registered on the running OPA server. Returns an array of `{ id, raw, ast }` records.

Apply a JSON Patch (RFC 6902) to the data document. Each operation is `{ op, path, value? }`.

Write or replace a value at the given data path. Body is sent as JSON.

Upload a Rego policy under the given ID. Replaces any existing policy with that ID. The policy is uploaded as raw text/plain -- OPA parses it on the server side.

Evaluate a decision against the running OPA server. POSTs to the data path with `{input}` and returns whatever the rule produces. Use this to ask the server "given this input, what does data.X.allow say?"

Return the running OPA server configuration via `GET /v1/config`. Returns the same underlying document as `opa_config` but presented under a `status` key as a convenience for agents that want to check "what is running" rather than "what was the server configured with". The response includes bundle settings, decision-log settings, and plugin configuration as OPA reported them at startup.

Benchmark a Rego query against a policy + input with `opa bench`. Returns statistical timing data: iterations, ns/op, and allocation counts. Use this to spot slow rules.

Return OPA capabilities -- the available builtins, future keywords, features, and WASM ABI versions. With `current: true`, returns the running OPA's capabilities. With `version: "v0.69.0"`, returns those of a specific version. With neither, lists available named versions. By default (`names_only: true`), returns only builtin names and count to stay within response size limits; pass `names_only: false` for full type signatures and documentation.

Type-check Rego with `opa check`. Returns `{ valid: true, errors: [] }` on success, or a list of structured diagnostics with file/line locations on failure. Provide either `source` for inline checking or `paths` for file/directory checking.

Validate that a Rego policy's input.* field references are consistent with a JSON Schema using `opa check --schema`. Every field the policy reads from `input` must exist in the schema; mismatches surface as rego_type_error diagnostics with file/line locations. Returns `{ valid: true, errors: [] }` when all references match the schema, or `{ valid: false, errors: [...] }` with structured diagnostics when they do not. Accepts the schema inline (pass the `schema` output of `rego_infer_input_schema` directly as `inlineSchema`) or as a path to an existing JSON Schema file on disk (`schemaPath`). Provide `source` for inline Rego or `paths` for file/directory checking.

Run partial evaluation on a query -- substitute known values and return the residual policy. Defaults `unknowns` to `["input"]` (treat input as unknown), so the residual encodes "given input X, this is what would have to be true." Use this for offline policy slicing or pre-computing decision sets.

Run opa test --coverage and return a per-file breakdown of uncovered line ranges. Identifies which rules or branches are not yet exercised by tests. Files are sorted by coverage ascending so the worst-covered files appear first. Use threshold to limit the report to files below a target coverage percentage.

Static dependency analysis for a Rego reference. Given a target ref like "data.example.allow", returns the base document references (input/data leaves) and virtual document references (rules) it depends on, transitively.

Parse a Rego policy and return a structured summary: package, imports, and rules. Each rule reports clauseCount (how many definitions share the name), isDefault (true if any clause is a default), hasArgs, bodyLength (total body expressions across all clauses), and inline annotations. Useful as the first step in any "what does this policy do" workflow.

Evaluate a Rego query against a policy and an input document using `opa eval`. Returns the standard `{result: [...]}` shape. The bread-and-butter authoring tool.

Evaluate with `--coverage` and return per-line coverage data. Useful for verifying that tests actually exercise the rules they're meant to.

Evaluate with `--explain=full` and return a structured trace alongside the result. Use this when an agent needs to see why a rule fired (or didn't) -- the trace is the basis for `rego_explain_decision`.

Evaluate with `--profile` and return per-rule timing and evaluation counts. Use this to find hot rules in slow policies.

Evaluate a Rego query with full tracing and return a structured trace plus per-rule fired/not-fired summary. Use this when you need to answer "why was this denied?" -- the agent reads the structured trace and narrates the cause without re-implementing the trace parser.

Diagnose why a fully-qualified Rego query (e.g. "data.authz.allow") produces no value. Combines a plain eval, a full-trace eval, and per-condition AST analysis to identify the exact body expression blocking each rule. Handles both runtime failures (trace-based) and indexer elimination (standalone condition eval). Returns a structured breakdown of which conditions blocked each rule plus a human-readable summary.

Run regal fix to automatically apply mechanical fixes for the five rules regal 0.30.0 supports: opa-fmt, use-rego-v1, use-assignment-operator, no-whitespace-comment, and directory-package-mismatch. Use dryRun: true to preview changes before modifying files. NOTE: directory-package-mismatch moves files to match their package path -- use disable: ["directory-package-mismatch"] to skip it. Files with uncommitted git changes require force: true. Requires regal.

Format Rego source code using `opa fmt`. Returns the formatted source and a `changed` flag indicating whether the input was already canonical. When the source uses string interpolation ($"..." or $`...` syntax) and OPA v1.12.0 or v1.12.1 is detected, the tool warns about or blocks formatting due to a known OPA bug that corrupts \{ escape sequences (fixed in OPA v1.12.2).

Run `opa fmt --write` to canonically format one or more Rego files or directories in place. Use `dryRun: true` to preview which files would change without modifying them. Returns a list of files that were (or would be) reformatted. Unlike `rego_format` which returns formatted source as a string, this tool writes directly to disk. Supports `regoV1`, `v0Compatible`, and `v1Compatible` flags for version-specific formatting. If any file cannot be parsed, the operation is aborted and no files are written.

Generate a `*_test.rego` skeleton from a policy. Parses the AST, finds each non-test rule, and emits one stub test per rule. Existing `test_*` and `todo_test_*` rules are skipped automatically -- only testable production rules get stubs. The AST is walked to infer which `input.*` fields the policy accesses; the inferred shape is used as the placeholder `with input as {...}` in each stub, so the developer only needs to fill in realistic values rather than guess the structure. With `tableStyle: true`, each stub uses an `every tc in cases { ... }` loop so you can add multiple input/expected pairs without duplicating assertion code. The `inferredInputShape` field in the response shows the detected shape for reference.

Statically analyse one or more Rego policies and return a JSON Schema (draft-07) object describing every input.* field the policies read. Uses opa parse for AST-level analysis -- no running OPA server required. Correct starting point for writing integration tests, configuring opa check --schema validation, or documenting a policy API. Accepts inline source, individual files, or directories (walked recursively for *.rego files).

Inspect an OPA bundle, policy directory, or single Rego file with `opa inspect`. Returns manifest data, namespaces, rule annotations, and (if signed) signature metadata.

Lint Rego source with the Regal linter. Returns categorized violations (style, bugs, idiomatic, performance) with file/line locations. Requires `regal` on PATH or `REGAL_BINARY` set; returns REGAL_NOT_FOUND otherwise. When called with inline `source`, location-bound rules whose verdict depends on the on-disk path (`directory-package-mismatch`) are auto-disabled to avoid temp-file false positives, and `location.file` is reported as `<inline>` instead of the randomized temp path. Re-enable those rules via `enable` if your workflow actually needs them.

Migrate Rego v0 source to Rego v1 syntax in two phases: (1) `opa fmt --rego-v1` auto-fixes reserved keywords (`if`, `contains`, `every`, `in` in rule heads) and adds `import rego.v1`; (2) `opa check --v1-compatible` validates the migrated source and reports any remaining issues that cannot be auto-fixed (e.g. removed builtins, semantic conflicts). Returns the migrated source and a `changed` flag even when check finds remaining errors -- this lets you inspect what changed and fix the remainder manually. If the source is completely unparseable, returns `INVALID_REGO`.

Parse Rego source to a JSON AST using `opa parse`. Returns the AST as a tree of nodes (package, imports, rules, expressions, terms). Use this when you need to introspect policy structure programmatically.

Share a Rego policy with teammates or create a reproducible example by publishing it as a public GitHub Gist. Returns { gistUrl, rawPolicyUrl, id }: the gistUrl renders the policy with syntax highlighting on github.com; the rawPolicyUrl can be passed directly to OPA (`opa eval -d <rawPolicyUrl> <query>`) or used as a data source in Conftest. When query, input, or data are supplied, a metadata.json file is bundled into the Gist so recipients have the full evaluation context to reproduce results. Each call creates a new Gist -- use the returned id to reference it later. Requires GITHUB_TOKEN in the environment (GitHub personal access token with the "gist" scope); returns GITHUB_TOKEN_MISSING with setup instructions if unset.

Evaluate the same query against two policies (or two versions of the same policy) and compare the results. Both evaluations run in parallel. Returns `equal: true/false`, the raw result from each side, and `changedPaths` -- the dot/bracket paths that differ. Useful for verifying that a refactor preserves behavior, or understanding exactly where two policies diverge. Each side takes either inline source (sourceA/sourceB) or a file/directory path (pathA/pathB). The same input and query are used for both evaluations.

Run regal lint restricted to the security and bugs categories across one or more policy directories. Returns findings grouped by severity (high/medium) with remediation guidance. Use this for a periodic fleet-wide security sweep rather than per-file style review. Requires regal.

Map common Rego compile errors and Regal lint findings to mechanical fix suggestions. Pass diagnostics from `rego_check` or `rego_lint`. Returns one suggestion per input diagnostic; confidence is `high` for well-known patterns, `medium` for partial matches, `low` for everything else.

Run Rego unit tests with `opa test`. Returns aggregate pass/fail counts plus per-test records. Tests live in `*_test.rego` files; rule names beginning with `test_` are picked up automatically. Use `runPattern` to filter by name regex; when no tests match, the error hint includes the pattern you supplied. Use `threshold` to gate on minimum coverage (returns COVERAGE_BELOW_THRESHOLD on failure). Use `varValues: true` with `verbose: true` to include local variable bindings in the trace -- essential for debugging table-driven tests written with `every tc in cases { ... }` to identify which case caused a failure. When tests use the `test_X[case]` parametrized form, the output includes `parameterizedGroups` mapping each base test name to its case records. Use `ignorePatterns` to exclude generated or fixture files. Use `bundle: true` when testing bundle-structured policy directories. Use `timeout` to raise the per-test limit beyond OPA's default 5s. Note: enabling `coverage` or `threshold` switches OPA to coverage-report output mode -- per-test counts are unavailable but `coverage` and `coveragePct` fields are populated.