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

Annotations already indicate readOnlyHint=true, destructiveHint=false, and idempotentHint=true, so safety is covered. The description adds valuable behavioral context beyond annotations by enumerating the response contents (verbatim flag, timestamp, moment link, surrounding context, permanent card URL, share image, and Markdown), which helps the agent anticipate the output structure. No contradiction with annotations.

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, compact sentence that front-loads the action and then lists the included data fields. It is informative without being verbose, and every clause contributes to understanding the tool's function and output. The structure is clear and easy to scan.

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 single-parameter tool with annotations covering safety and no output schema, the description is fully adequate. It covers what a yank is, how to identify it, and what the response includes. There are no missing pieces that would prevent an agent from calling the tool correctly. Even without an output schema, the description preemptively details the return payload.

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 schema provides a single 'slug' parameter with an example, but the description adds semantic meaning by explaining the slug is 'the last path segment of a yank.info/y/<slug> URL'. This clarifies how to derive the value, going beyond the schema's example. With 100% schema coverage, the description adds supplementary context that improves parameter understanding.

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 'Fetch' and the resource 'a yank', and details exactly what is retrieved (five extracted lines, verbatim flag, timestamps, etc.). It defines the identifier (slug) as the last path segment of a yank.info/y/<slug> URL, making the tool's function unambiguous and distinct from sibling tools like search_lines or recent_yanks.

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 the tool should be used when you have a specific slug and need comprehensive details of a single yank. However, it does not explicitly mention when not to use it or compare with sibling tools like check_quote or get_lines_for_url. There is no guidance on alternative selection, but the required parameter and identifier format make the usage context clear enough.

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