List changed files

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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the bar is lower; the description still adds real value by disclosing the path-policy interaction ('Paths ... are always listed, even ones whose contents the path policy hides') and the cost profile. It does not mention pagination or limits on large change sets, which is the remaining gap.

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?

Three short sentences, front-loaded with the core purpose, then the activation cue, then the policy caveat. Every sentence carries distinct information with no repetition of the schema or annotations.

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?

An output schema exists, so return values need not be spelled out, yet the description still summarizes them plus a caveat the schema cannot express. For a read-only four-parameter listing tool, an agent has everything needed to invoke and interpret it correctly.

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?

Schema description coverage is 100%, so base, head, mode, and paths are already fully documented in the schema. The description only implies the two-commit comparison and does not expand on the merge-base vs direct mode distinction or path filtering, so baseline 3 applies.

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?

States a specific verb and resource ('List files changed between two commits') and enumerates the returned fields (status, line counts, test flag), so the agent knows exactly what it gets. It also names the sibling get_diff, distinguishing this cheap listing tool from the content-reading one.

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?

Gives an explicit sequencing rule: 'call this before get_diff to decide what to read', which routes the agent between the two siblings on a clear condition. The cost note ('Cheap') supplies the rationale for preferring this over fetching diffs outright.

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