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Conftest test

conftest_test
Read-onlyIdempotent

Evaluate configuration files against Rego policies with conftest. Get per-file, per-namespace pass/fail/warn results to pinpoint which policy rules fired.

Instructions

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. Policies are executed by conftest and can call OPA built-ins such as http.send.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
dataNoPaths to directories from which additional data will be loaded for the Rego policies. Each path must be inside an allowed root.
filesNoFilesystem paths to configuration files to evaluate (YAML, JSON, HCL, Dockerfile, etc.). Each path must be inside an allowed root (OPA_MCP_ALLOWED_PATHS). Mutually exclusive with `inlineConfig`.
parserNoForce a specific parser for all input `files` via conftest's global `--parser` flag, overriding extension-based detection. Useful for files whose extension does not match their format (e.g. parse a `.tfstate` file as `json`). One of: cue, dockerfile, dotenv, edn, hcl1, hcl2, hocon, ignore, ini, json, jsonnet, nginx, properties, spdx, textproto, toml, vcl, xml, yaml. For `inlineConfig`, prefer `inlineConfigParser`.
policyNoPath to a directory or file containing Rego policies. Must be inside an allowed root (OPA_MCP_ALLOWED_PATHS). Mutually exclusive with `inlinePolicy`. Omit to let conftest use its default `./policy` directory.
combineNoCombine all configuration files into a single input document before evaluating. Useful when policies need to inspect relationships across multiple files.
namespaceNoRego namespace (package name) to test against. Defaults to `main`. Use `allNamespaces: true` to test all discovered namespaces instead.
failOnWarnNoReturn `passed: false` even when only warnings (no hard failures) are present.
inlineConfigNoInline configuration content to evaluate (e.g. a Kubernetes manifest as a YAML string). Mutually exclusive with `files`. Defaults to YAML format; set `inlineConfigParser` to override.
inlinePolicyNoInline Rego policy source. Written to a temporary directory and passed as `--policy`. The policy should declare `package main` (or match the `namespace` parameter). Mutually exclusive with `policy`.
allNamespacesNoTest policies found in all discovered namespaces. Overrides `namespace`.
inlineConfigParserNoParser to use for `inlineConfig`. One of: cue, dockerfile, dotenv, edn, hcl1, hcl2, hocon, ignore, ini, json, jsonnet, nginx, properties, spdx, textproto, toml, vcl, xml, yaml. Defaults to yaml. Ignored when `files` is used (conftest infers the parser from each file's extension, unless `parser` is set).

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. Changed4 schema fields changedv0.5.0
    • changedInput schema / properties / inlineConfigParser / description
      Previous value: -"Parser to use for `inlineConfig`. Valid values: yaml (default), json, toml, hcl1, hcl2, ini, xml, dotenv, cue, jsonnet, properties, edn, hocon, dockerfile. Ignored when `files` is used (conftest infers the parser from each file's extension, unless `parser` is set)."New value: +"Parser to use for `inlineConfig`. One of: cue, dockerfile, dotenv, edn, hcl1, hcl2, hocon, ignore, ini, json, jsonnet, nginx, properties, spdx, textproto, toml, vcl, xml, yaml. Defaults to yaml. Ignored when `files` is used (conftest infers the parser from each file's extension, unless `parser` is set)."
    • addedInput schema / properties / inlineConfigParser / enum
      Added value: +[
      +  "cue",
      +  "dockerfile",
      +  "dotenv",
      +  "edn",
      +  "hcl1",
      +  "hcl2",
      +  "hocon",
      +  "ignore",
      +  "ini",
      +  "json",
      +  "jsonnet",
      +  "nginx",
      +  "properties",
      +  "spdx",
      +  "textproto",
      +  "toml",
      +  "vcl",
      +  "xml",
      +  "yaml"
      +]
    • changedInput schema / properties / parser / description
      Previous value: -"Force a specific parser for all input `files` via conftest's global `--parser` flag, overriding extension-based detection. Useful for files whose extension does not match their format (e.g. parse a `.tfstate` file as `json`). Valid values: yaml, json, toml, hcl1, hcl2, ini, xml, dotenv, cue, jsonnet, properties, edn, hocon, dockerfile. For `inlineConfig`, prefer `inlineConfigParser`."New value: +"Force a specific parser for all input `files` via conftest's global `--parser` flag, overriding extension-based detection. Useful for files whose extension does not match their format (e.g. parse a `.tfstate` file as `json`). One of: cue, dockerfile, dotenv, edn, hcl1, hcl2, hocon, ignore, ini, json, jsonnet, nginx, properties, spdx, textproto, toml, vcl, xml, yaml. For `inlineConfig`, prefer `inlineConfigParser`."
    • addedInput schema / properties / parser / enum
      Added value: +[
      +  "cue",
      +  "dockerfile",
      +  "dotenv",
      +  "edn",
      +  "hcl1",
      +  "hcl2",
      +  "hocon",
      +  "ignore",
      +  "ini",
      +  "json",
      +  "jsonnet",
      +  "nginx",
      +  "properties",
      +  "spdx",
      +  "textproto",
      +  "toml",
      +  "vcl",
      +  "xml",
      +  "yaml"
      +]
  2. Changed2 schema fields changedv0.1.20
    • changedInput schema / properties / inlineConfigParser / description
      Previous value: -"Parser to use for `inlineConfig`. Valid values: yaml (default), json, toml, hcl1, hcl2, ini, xml, dotenv, cue, jsonnet, properties, dockerfile. Ignored when `files` is used (conftest infers the parser from each file's extension)."New value: +"Parser to use for `inlineConfig`. Valid values: yaml (default), json, toml, hcl1, hcl2, ini, xml, dotenv, cue, jsonnet, properties, edn, hocon, dockerfile. Ignored when `files` is used (conftest infers the parser from each file's extension, unless `parser` is set)."
    • addedInput schema / properties / parser
      Added value: +{
      +  "description": "Force a specific parser for all input `files` via conftest's global `--parser` flag, overriding extension-based detection. Useful for files whose extension does not match their format (e.g. parse a `.tfstate` file as `json`). Valid values: yaml, json, toml, hcl1, hcl2, ini, xml, dotenv, cue, jsonnet, properties, edn, hocon, dockerfile. For `inlineConfig`, prefer `inlineConfigParser`.",
      +  "type": "string"
      +}
  3. Addedv0.1.13

TDQS

A4.5/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover readOnly/openWorld/idempotent/destructive, and the description adds genuinely new behavioral facts: the external conftest binary requirement with the CONFTEST_NOT_FOUND failure mode, per-file/per-namespace result granularity, and the notable trait that policies can invoke OPA built-ins such as http.send, implying network side effects — which aligns with and extends the openWorldHint. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The purpose is front-loaded in the first sentence, and every subsequent sentence covers a distinct topic: result format, dependency and failure mode, input options, defaults, and policy capabilities. At roughly 130 words it is dense but has no filler and nothing that merely repeats the schema.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a complex 11-parameter tool with no output schema, the description compensates well: it states the return shape (per-file, per-namespace pass/fail/warn), the external dependency, defaults, and the mutual-exclusion pairs echoed in the schema. Nothing an agent needs to call it correctly and interpret results is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all 11 parameters are already documented with types, mutual-exclusion constraints, and defaults. The description reinforces the two-axis mental model (config via files/inlineConfig, policy via policy/inlinePolicy) and the default policy directory, but adds little per-parameter meaning beyond what the schema provides. Baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a precise verb+resource: 'Evaluate configuration files ... against Rego policies using `conftest test`', enumerating the accepted formats (Kubernetes manifests, Terraform plans, Dockerfiles, Helm charts, etc.). This clearly differentiates the tool from the rego_* siblings, which operate on Rego source, and from conftest_verify/conftest_pull/conftest_push, which address other conftest workflows.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear operational context: two input axes (files vs inlineConfig, policy vs inlinePolicy), the mutually exclusive pairs, and the default `./policy` directory behavior when both policy options are omitted. However, it never names an alternative tool or states when not to use this tool, so an agent must infer differentiation from sibling names rather than explicit guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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