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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, covering safety and idempotency. The description adds that refs are opaque and expanded into full content, but does not disclose additional behaviors such as rate limits, authentication requirements, or error handling. Since annotations cover the core behavioral traits, the description's added value is minimal.

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?

The description is a single, front-loaded sentence that directly states the action and purpose. There is no wasted wording or redundant information, making it highly concise and well-structured.

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?

Given that the tool has an output schema, the description need not explain return values. The description covers what the tool does and where refs originate, which is sufficient for a simple one-parameter operation. It does not mention edge cases or invalid input handling, but the word 'opaque' implies that refs should be used as-is, and the output schema provides the expected return structure. Overall, it is complete enough for an agent to call the tool 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 coverage is 100% because the parameter 'refs' has a description identical to the tool description ('Opaque ref tokens from search/lookup hit records, to expand into full segment content'). The tool description does not add any extra meaning beyond what the schema already provides, so it meets the baseline for high coverage without adding 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 clearly states the verb 'Expand' and the resource 'opaque ref tokens' with a specific outcome 'full datasheet segment content'. It distinguishes itself from sibling tools like search, lookup, and get_specs by focusing solely on expanding refs into segment content, which is a unique operation among the listed siblings.

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 phrase 'from search/lookup' provides context that this tool is intended to be used after those operations, implying a prerequisite. However, it does not explicitly state when to use this tool versus alternatives, nor does it mention any scenarios where it should not be used. The guidance is implied rather than explicit.

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