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

Annotations only declare readOnly and openWorld, but the description goes far beyond: it discloses the exact scoring weights, tier thresholds, the underlying network calls (one GitHub search or one raw.githubusercontent download plus one npm/PyPI lookup per repo when withDownloads is true), rate limits (50 free calls/day), the auth mechanism (X-GitHub-Token header), and a local-run option. This is unusually rich behavioral context.

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?

Purpose and the sibling exclusion are front-loaded, and most sentences carry distinct information. It is dense and long, with the full scoring breakdown arguably more than an agent needs to select the tool, so it is slightly over-full rather than maximally tight.

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?

No output schema exists, yet the description fully characterizes the return values (0-100 score, tier labels, one-line verdict, full breakdown), plus cost, latency, auth, and rate limits. Nothing an agent needs to call it correctly is missing.

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%, so the baseline is 3, and the description adds real meaning: 'risingRank keeps that order' and 'sorted by score (starsRank keeps the stars order)' explain the ordering consequences of period, and it clarifies that withDownloads trades speed for registry data. The parameter coverage is strong; only minor format detail is absent from the description vs. 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 and resource (discover the most-starred GitHub repositories created in a time window, or period='rising' repos by weekly star gain), and explicitly distinguishes itself from recommend_repos. An agent can identify what this returns and how it differs from compare_repos/recommend_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 the alternative and the condition that selects it: "Not the right tool for picking a dependency... use recommend_repos for that," and it explains what each period value is for. Both when-to-use and when-not-to-use are covered.

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