jev-agent-tools-mcp

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Jev select tests

jev_select_tests

Read-only

Selects existing tests affected by a diff and returns runner commands without running or collecting tests, helping you plan which tests to execute.

Instructions

Select existing tests affected by a diff and return runner commands; this tool never runs or collects tests. Use when selecting existing affected tests can usefully change the execution plan; use native read/grep/bash for exact names and execution. base defaults to HEAD; paths are candidate test files or globs, not diff paths. Static discovery reads tracked files, literal project configuration and imports, without evaluating third-party config. Touched tests are selected for free; import closure includes unchanged intermediates and applicable pytest conftest fixtures. Remaining scenarios receive a changed-unit pointer; selected when 1-p(none) >= 0.5. Missing answers are selected; unavailable Jev falls back to all. Residual exported-unit checks report changed, run by no discovered test only within the discovered inventory, never global coverage or an obligation to add a scenario. Unsupported, unknown, calculated or unresolved runners keep that conclusion unsure and name the next manual action. Runtime and type tests are separate. Commands remain separate by cwd, config, project and framework; project options are preserved. At least 80% selected, uncertain names or unknown counts run the entire file. max_calls bounds Jev calls; unjudged tests remain selected. witnesses controls residual coverage checks (auto by default); pointers have no witnesses. This does not detect that a new test scenario is required.

Use Jev for a bounded semantic judgment when its answer could change an open decision or focus the next inspection, and the relevant evidence is available. Use decisive reading, search or authorized execution directly when it settles the question. Exact lookup, counting and runtime causality belong to native tools. A Jev call is not a prerequisite for a conclusion, a review or task completion; no explanation is needed for choosing native tools.

After an unavailable, refused or out-of-scope result, continue natively within the existing permissions; do not widen sharing or confinement to obtain a judgment. For uncertainty or missing evidence, inspect or obtain the decisive piece, or leave the conclusion open. Revisit Jev only when new evidence, a material context change or a new useful question makes the judgment useful; rewording unchanged evidence is not a reason to retry. There is no retry quota for genuinely changed evidence, and no certification is needed once decisive evidence settles the question. A reached cap or an unjudged result is not evidence of safety or zero affected tests.

Input Schema

Name	Required	Description	Default
`base`	No
`root`	No
`paths`	No
`max_calls`	No
`witnesses`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.4.0Nov 2, 2026

TDQS

A4.2/5.0

Behavior5/5

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

Annotations already declare readOnlyHint=true and destructiveHint=false, but the description adds substantial context beyond them: static discovery sources, fallback to all tests when Jev is unavailable, the 80% threshold for running whole files, max_calls keeping unjudged tests selected, and that residual exported-unit checks are inventory-scoped, not coverage obligations. It also warns it cannot detect that a new test scenario is required — a meaningful limitation disclosure.

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

Conciseness3/5

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

The first sentence is well front-loaded and the native-vs-Jev guidance is placed logically, but the text balloons to roughly 380 words of dense, hard-to-parse clauses including a probabilistic formula ('1-p(none) >= 0.5') that reads as implementation detail rather than invocation guidance. Several sentences could be trimmed without losing selection value.

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

Completeness4/5

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

An output schema exists, so return format need not be described, and the description covers the complex selection semantics, fallbacks and limits thoroughly. Its main omissions relative to its own complexity are the unexplained `root` parameter and the witnesses enum levels.

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 0% for all five parameters, so the description must carry the load. It explains base (defaults to HEAD), paths (candidate test files or globs, not diff paths), max_calls (bounds Jev calls, unjudged remain selected) and witnesses (controls residual checks, auto by default), but the `root` parameter is never mentioned and the off/auto/on enum values are not defined, leaving a real gap.

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

Purpose4/5

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

The opening sentence states a specific verb and resource — select existing tests affected by a diff and return runner commands — and explicitly negates what it is not (it never runs or collects tests). It does not name or differentiate against siblings like jev_check_diff or jev_ask, which leaves some work to the agent.

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

Usage Guidelines5/5

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

Explicitly states when to use it ('when selecting existing affected tests can usefully change the execution plan'), when to prefer native read/grep/bash, and the conditions under which a Jev judgment is warranted versus settled by direct evidence. It also covers retry/revisit policy and post-failure behavior, which is unusually complete 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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