Find similar repositories

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

Annotations already flag readOnlyHint/openWorldHint, so the safety profile is covered; the description adds real value beyond that — ranking rules ('how many topics they share, then by stars'), result composition, and a cost signal ('Uses up to 3 searches'). It stops short of stating failure/empty behavior when the seed repo has no topics or doesn't exist.

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?

Three tightly packed sentences, front-loaded with the core action and mechanism before the detail. The parenthetical field list is long but justified because there is no output schema; still, it is the least dense portion.

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 no output schema, the description correctly carries the return-value burden (field list plus shared topics) and discloses ranking and search cost. Remaining gaps are edge-case behavior (no topics, invalid seed repo) rather than anything needed to call it correctly.

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 schema already documents owner, repo, limit, min_stars, and same_language with defaults and bounds. The description only loosely reinforces same_language ('optionally its language') and says nothing extra about limit or min_stars, so baseline 3 applies.

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+resource ('Find repositories similar to a given one') plus the mechanism ('using its topics (and optionally its language)'). It also anchors itself against the sibling search_repositories by noting result-field parity, so an agent can distinguish it from search_repositories and compare_repositories without reading schemas.

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 usage context is clear: you must already have a seed repo (owner/repo), and similarity is topic-driven with an optional same-language narrowing. However, it never explicitly names an alternative to prefer or states a when-not condition (e.g., 'use search_topics if the repo is unknown').

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