github_repos_list_languages

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

With readOnlyHint, idempotentHint and openWorldHint already covering the safety profile, the description still earns credit by disclosing the return shape (an object keyed by language) and the absence of pagination, which matters since no output schema exists. It does not mention auth requirements or rate limits, so it is not fully exhaustive.

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?

A single tightly written sentence that front-loads the action and resource, then appends the two facts an agent needs (bytes per language, no paging). Zero filler.

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 two-parameter read-only tool with a fully documented schema and no output schema, the description supplies everything missing: what it returns, its keying, and that there is no pagination to handle. Nothing an agent needs to call it correctly is absent.

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% and both required parameters (owner, repo) are documented in the schema, so the baseline is 3. The description adds no formatting or case-sensitivity guidance beyond what the schema already provides.

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) and resource (a repository's languages) and adds the payload detail (bytes of code each). An agent immediately knows this is the language-breakdown read, distinct from the GitHub search tools among the siblings.

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?

Provides clear context for use — 'the quickest way to find out what a repository is written in before reading any of it' — which tells the agent when this tool is the right first step. It does not, however, name an alternative tool or state exclusions, so it stops short of full routing guidance.

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