Churn hotspots

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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real edge-case behavior beyond them: renames are followed (old commits counted under current name), deleted files and merge commits are excluded, and the 'hint' only appears for files with >=3 commits in the top decile. Missing details like large-repo performance or output ordering limit it below 5.

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?

A single front-loaded sentence leads with the core action before enumerating behavior. It is dense but every clause (rename handling, exclusions, hint rule) carries information, so little is wasted.

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?

With an output schema present, return-value explanation is unnecessary, and the description covers exclusions, rename handling, and the derived 'hint'/'churn_percentile' fields. It is complete for calling the tool correctly; only sibling-relative routing guidance is absent.

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 top/since/repo_path are already fully documented. The description adds only indirect meaning (top-decile and >=3-commit thresholds that relate to 'top') rather than syntax or format guidance beyond the schema.

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 (rank) and resource (frequently changed files / churn hotspots) and enumerates the metrics returned (commits per file, lines added/deleted). The scope is clearly distinguishable from siblings like file_history or change_coupling, though it never names an alternative to route against.

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 implies when the tool is useful (identifying churn-heavy files as refactoring/extra-review candidates) but gives no explicit when-to-use or when-not-to-use guidance relative to siblings such as bus_factor, knowledge_risk, or change_coupling.

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