github_user_summary

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

With no annotations supplied, the description carries the full burden and does well on the important traits: it discloses the auth model (no token required) and a real behavioral limit (private repos are invisible to the public API by design). It does not cover error behavior for a nonexistent username or rate limiting, which is why it falls short of a 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?

Two sentences, front-loaded with the resource and its contents, followed immediately by the data-visibility constraint. Nothing is repeated and every clause adds information an agent would otherwise have to guess.

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 one-parameter, read-oriented lookup with an output schema already documenting returns, this covers purpose, scope, and visibility limits adequately. The remaining gap is edge-case behavior (nonexistent user, rate limits) and parameter format, which is minor given the tool's simplicity.

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 0% for the single 'username' parameter, so the description would need to compensate. It does not add format detail such as whether this is the login handle versus display name, case sensitivity, or whether a URL is accepted, though the parameter name itself is largely self-documenting.

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 names a specific resource (a GitHub user) and enumerates exactly what the summary contains: profile, repo count, total stars across public repos, and most-used languages. That is concrete enough that an agent can distinguish it from repo-scoped siblings like repo_health and repo_compare without opening a 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?

Scope is stated ('public data only, no token'), which implies when the tool is applicable, but there is no explicit when-to-use guidance or named alternative (e.g., 'use repo_health for a single repository'). The agent must infer that this is the user-level overview tool rather than a repo-level one.

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