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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds useful behavioral context: the input must be an indexed URL, and matching is semantic rather than lexical. It does not describe error behavior for non-indexed URLs, result ordering, or output format, but with the read-only annotation the bar is lower and the added context earns a mid-range score.

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 efficient sentence that front-loads the core behavior and then adds a useful semantic distinction. It earns its place without redundancy. It is slightly lean, but not to the point of harming clarity.

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 two-parameter read-only tool, the description covers the core purpose and the key input constraint. However, it does not explain the 'limit' parameter, the return shape, or behavior when the given URL is not indexed. Since there is no output schema and sibling tools like fetch_page and find_passages exist, a little more detail would make the description fully self-sufficient.

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 50%: the 'url' parameter is described in the schema, but 'limit' is not. The description reinforces the meaning of 'url' by requiring it to be an indexed page, but it adds nothing about the 'limit' parameter or its default/maximum. Since the schema leaves half the parameters undocumented and the description does not compensate, this is a meaningful gap.

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 ('return') and resource ('other indexed pages with similar content'), and adds a clear distinguishing mechanism: comparing 'by meaning rather than shared keywords.' This effectively separates it from keyword-based sibling tools like search and search_batch. The title is also informative and matches the description.

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 when to use the tool: when you want semantic similarity between indexed pages rather than keyword matches. However, it does not explicitly name alternative tools or state exclusions, such as 'use search for keyword-based retrieval.' The guidance is present but left to inference rather than being directly actionable.

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