Read a repository README

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

With no annotations supplied, the description carries the full burden, and it does the single most important thing: it discloses that the returned text is untrusted third-party content and must not be treated as instructions, including a concrete list of the dangerous categories (running commands, changing settings, contacting anyone). It does not mention authentication requirements, rate limits, or what happens when a repository has no README or a truncated one.

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 purpose and decision context come first, and the safety constraint follows immediately. Every clause contributes information the agent needs and nothing is repeated from the schema.

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 tool with no output schema, the description covers purpose, decision context, and the critical trust-boundary warning. The remaining gap is return-shape guidance - whether the full README text comes back, whether it may be truncated, or what a missing README yields - which matters because no output schema exists to answer it.

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% for the single parameter, and the schema already labels it 'GitHub repository URL', so the baseline is 3. The description adds no format guidance beyond that - it does not clarify whether full URLs, owner/repo shorthand, or branch-specific paths are accepted.

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 a specific verb ('Fetch') with a specific resource ('a GitHub repository's README') and states the downstream intent ('so you can judge whether it really does the user's task'). It does not name or contrast with the siblings search_repositories or assess_repository, so the boundary between reading a README and assessing a repository is left implicit.

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 clause 'so you can judge whether it really does the user's task' gives a clear context for when this tool is appropriate, which is a meaningful usage anchor rather than a bare capability statement. There are no explicit exclusions or named alternatives, so the agent must infer that assess_repository covers the broader evaluation case.

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