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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered by structured data. The description adds genuinely new behavioral context: the result is cached and no generation is triggered. However, it is silent on the most important behavioral question for a cache-only read — what happens on a cache miss (empty result, error, or stale content) — and gives no hints about size or structure of the returned Markdown beyond the format.

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 short sentences, zero filler, with the core behavior (cached read) front-loaded and the caveat immediately after. Nothing is repeated from other fields or padded.

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?

No output schema, so the description carries the return-value burden, and it does state the return type (Markdown). But it omits cache-miss behavior and any parameter format guidance, which are the two things an agent still needs to call this 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 description coverage is 0% with two required parameters, owner and repo, neither of which has a description. The description only alludes to 'a repo' and does not clarify the owner/repo split, accepted formats, or whether org-scoped names work. With low coverage the description has to compensate, and it does not.

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?

Specific verb and resource: 'Return the cached AI "explain this codebase" Markdown for a repo.' The agent knows exactly what comes back. It does not name the obvious sibling, merjax_repo_explain_codebase, which likely generates the artifact, so differentiation 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?

Gives a clear exclusion — 'Pure read — never triggers a new generation' — and redirects to an alternative ('use the web UI for that'). The redirection is to the UI rather than to the sibling tool merjax_repo_explain_codebase, which is the alternative an agent could actually call.

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