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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real value beyond them by clarifying that the result is the *full text* (not a snippet) and by showing the id shape with prefixes ('service:', 'case-study:') that hint at document types.

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 sentence with zero filler, front-loading the return value and then the lookup key. Every clause 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?

For a one-parameter read tool with rich annotations and no output schema, the description covers what it returns and what input it needs. Only error/not-found behavior for an unknown id is left unstated, a minor gap given the simplicity.

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%, so baseline is 3; the description exceeds it by illustrating the id format with two concrete prefixed examples, which is meaning the schema's 'Document id returned by search' does not convey. It still omits what happens on a malformed or unknown id.

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+resource ('Returns the full text of a document') and the lookup key ('by its id'), which clearly distinguishes it from `search`, which only returns references. It does not explicitly name `search` as the sibling it complements, keeping it just 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?

'from search' and the schema note 'Document id returned by search' make the intended workflow (search first, then fetch) clear without spelling out an alternative. There are no explicit exclusions or failure conditions, but for a one-step lookup the context is sufficient.

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