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

Annotations already declare readOnly, idempotent, non-destructive, and open-world. The description adds meaningful context beyond them: results are scoped to HEAD (committed state, not working tree) and filtered to 'readable' files, implying permission-based filtering.

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 front-loaded sentence with no filler; the scope (one repo, HEAD) comes before the optional modifier. Every clause carries information.

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?

There is no output schema, so the description should clarify the shape of the result, but it never says whether paths are recursive, relative, or whether directories appear. It is minimally adequate for a two-parameter listing tool but leaves the agent guessing at return structure.

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 0%, so the description carries the burden, and it does explain both parameters: 'repo' selects the repository and 'prefix' optionally narrows the listing. However, it omits format details such as whether the repo is owner/name, whether listing is recursive, and whether directories are included.

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 gives a specific verb and resource: 'List the readable files of one ce repo at HEAD', which an agent can distinguish from siblings like source_read (content) and source_repos (repo enumeration). It does not explicitly name an alternative, and the abbreviation 'ce' is unexplained, so it stops short of a 5.

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 only guidance is that a path prefix is optional, which is parameter semantics rather than tool selection advice. There is no statement of when to use this versus source_read, source_search, or source_repos, and no exclusions.

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