compare_repos

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

With no annotations, the description carries the behavioral burden. It discloses the return format as a table, lists the exact data points, and signals imprecision with 'approximate contributor count'. It does not mention rate limits or network dependency, but the compare operation is clearly non-mutating and well described.

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 with no filler. The first sentence front-loads the action, input count, and output contents; the second gives usage positioning. Every sentence earns its place.

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?

The description tells the agent exactly what to input and what fields will appear in the result, which is enough for a simple comparison tool with one well-schema'd parameter. Minor caveats about error behavior or rate limits are not stated, but they are not essential for correct invocation.

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?

The schema already fully documents the single 'repos' parameter with min/max items and an example. The description repeats the 2-4 constraint and GitHub scope but adds no meaningful semantics beyond the schema. Baseline 3 is appropriate given the 100% schema coverage.

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 uses the specific verb 'Compare', names the resource '2-4 GitHub repos', and states the output form: 'side by side as a table' with a clear list of fields. This distinguishes it from sibling tools like search_github_repos and get_repo_overview.

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 description explicitly says 'Use this to help decide between finalists after search_github_repos', giving a clear when-to-use context. It contrasts with 'eyeballing separate results' but does not name alternative tools for when not to use it, so it stops short of a full exclusion set.

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