run_tests

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals key traits: the command is fixed (never LLM-supplied), the operation is read-only ('Does not modify system state'), and the repo path must be within allowed roots. These are important for an agent to use the tool safely and correctly, though it does not cover return format details (handled by output schema).

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

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

The description is two short paragraphs, front-loaded with the primary purpose. Every sentence adds distinct information: operation, security constraint, return contents, usage context, and side-effect guarantee. No redundant or filler content.

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

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

Given the simplicity of the tool (single parameter) and the presence of an output schema, the description covers all critical aspects: what it does, when to use it, constraints, and non-modification guarantee. Minor gaps like timeout or concurrency behavior are not present, but for a read-only test runner these are not essential.

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

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

The schema for the only parameter 'repo' has no description (0% coverage). The description adds the constraint 'repo path must be within allowed roots', which provides some semantic value beyond the schema. However, it does not clarify path format or what constitutes a valid repository, leaving the agent to infer from the noun 'repository' used in the text.

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

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

The description clearly states a specific verb ('Runs') and resource ('pytest in a repository'), and specifies the output (pass/fail status, summary, list of failing tests). It is immediately distinguishable from all sibling tools, which are system monitoring and file/git operations.

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

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

The description explicitly says 'Use this when investigating test failures or verifying that changes haven't broken tests.' This provides clear context for when to invoke the tool. It does not mention alternatives or exclusions, but given the sibling set, no direct alternative exists, so the guidance is adequate.

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