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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the read-only nature is known. The description adds the specific scope of documents that can be fetched, which is valuable context beyond the annotations. It does not contradict annotations and adds some behavioral detail, though it omits return format or error behavior, so a 4 fits.

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 that is front-loaded with the verb and resource, then lists the allowed sources. Every word earns its place; there is no fluff or redundant phrasing. It is maximally concise while remaining informative.

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 simple one-parameter fetch tool with no output schema and read-only annotations, the description is nearly complete. It explains what the id is for and what sources are valid. However, it does not explicitly state what the tool returns (the document content), though this is implied. A minor gap, so a 4 is reasonable.

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?

The input schema covers 100% of the parameter with the description 'Document id from search'. The tool description repeats this without adding new syntax or format details. Since schema coverage is high, the baseline of 3 is appropriate; the description adds no extra semantic value.

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 states a specific verb ('Fetch'), a resource ('document by id'), and enumerates the allowed document sources (menu, help, auth, tool:<name>, or a mint). It clearly distinguishes from sibling search tools that return lists rather than a single document. The purpose is unambiguous and informative.

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 description implies usage after a search by mentioning 'from search' and enumerating document types, but it does not explicitly say when to use this vs alternatives or mention any exclusions. It provides context but not a full routing guide, so a 4 is appropriate.

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