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

Annotations already carry readOnlyHint=true and openWorldHint=true, so safety and external-API context are covered. The description adds a genuinely useful behavioral trait beyond them: results are ordered by contribution count, which shapes how the agent interprets the output.

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 sentences, zero filler. The core scope is front-loaded and the alternative routing follows immediately.

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 no explanation, and annotations cover the safety profile. Purpose, ordering, and sibling routing are all present; only explicit pagination behavior is omitted, which is minimal given the schema hints at page/per_page.

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% with self-explanatory parameters (owner, repo, page, per_page). The description adds no syntax, default, or format detail beyond the schema, so the baseline 3 is correct.

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 (List), resource (a GitHub repository's contributors), and a behavioral detail (ordered by contribution count). The agent can distinguish this from github_repo and github_user_repos without opening any schema.

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?

Explicitly names two alternatives (github_repo for repo details, github_user_repos for an owner's public repos) and the conditions that route to them. It lacks an explicit 'use this when...' trigger or a when-not statement, so it stops just short of full coverage.

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