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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false, covering safety and idempotency. The description adds valuable context beyond annotations: it specifies the output includes 'relevant passages with author attribution and canonical source URLs', and clarifies the fiction filtering behavior. This goes beyond what annotations provide, giving the agent a clear behavioral model.

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 moderately long but effectively front-loaded: it opens with the core purpose, then lists example topics for guidance, and closes with output details and the fiction caveat. Every sentence contributes value, though the topic list could be slightly trimmed without loss. Overall it is well-structured and readable.

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?

The tool has an output schema, so return values are documented. The description covers the search scope, typical queries, output format, and the fiction filter, which is comprehensive for a search tool. It does not mention pagination or limit behavior, but that is covered by the schema's limit parameter. Given the annotations and schema richness, the description is sufficiently complete for an agent to invoke it 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 description coverage is 100% (both query and limit have descriptions). The description does not add syntax or format details beyond the schema, but it does provide a rich list of example query topics, which implicitly guides parameter usage. Since the schema already documents both parameters well, a baseline of 3 is appropriate; the description adds marginal value on parameter meaning.

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 tool searches published historical research and companion guides for factual material, with a specific verb (search) and resource. It lists a comprehensive set of topics it covers, which distinguishes it from the more specific sibling tools (get_guide, get_historical_figure, get_sources) that likely retrieve single items. The purpose is unambiguous and actionable for an agent.

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 provides clear context for when to use the tool by enumerating many historical topics it addresses, and it explicitly states the fiction-returning condition ('only when the user explicitly asks for books, novels, historical fiction or further reading'). However, it does not explicitly mention the sibling tools as alternatives or state when NOT to use it (e.g., when a specific guide or figure is needed). This is a minor gap but the guidance is still strong.

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