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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the trailing 'Read-only.' merely restates structured data. The description does add real value by disclosing the ranking metric (commits plus PRs merged) and the temporal window, but says nothing about tie-breaking, result ordering stability, or pagination behavior.

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?

Two tight sentences with the core action front-loaded and the use cases following immediately. The standalone 'Read-only.' sentence is the only low-value element since it duplicates readOnlyHint=true, but it costs almost nothing.

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?

For a simple, fully optional-parameter read tool with complete schema coverage and no output schema, the description covers purpose, scope, and use cases adequately. The one remaining gap is return shape — an agent cannot tell whether contributor identity, per-contributor commit/PR counts, or rank fields come back — which a short clause could have closed.

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 coverage is 100% and both parameters already document their defaults and the max of 50, so the schema carries the semantics. The description reinforces the concept of a time window and clarifies that ranking is by commits and merged PRs, but adds no format details, units, or edge cases 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?

The description gives a specific verb and resource ('List the most active contributors') plus the ranking basis ('commits and PRs merged') and the scoping dimension ('over a time window'). That clearly separates it from list_team_members or get_developer, though it never names a sibling explicitly to make the contrast airtight.

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?

It provides concrete when-to-use context: identifying key contributors, spotting bus-factor risks, or recognizing top performers. There is no when-not-to-use guidance and no named alternative for the roster-style case (e.g., list_team_members), which keeps it below a 5.

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