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

Annotations already carry the safety profile with readOnlyHint=true and destructiveHint=false. The description adds the useful provenance detail that ids come from search results, but it does not disclose additional behavioral nuances. This is adequate but minimal, given the annotation coverage.

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 sentence that is front-loaded with the action and resource. Every phrase earns its place, and there is no wasted repetition of the schema or annotations.

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 one-parameter read-only tool with annotations and an output schema, the description covers the resource type and the id source. The main gap is the lack of explicit distinction from the sibling 'get_backtest', which leaves some ambiguity about which tool to invoke for backtest-related ids.

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 has one string parameter with no description (0% coverage), so the description must compensate. It does add meaning by specifying that the id is one 'as returned by search', giving the agent a clear source for valid IDs. For a single simple parameter, this is sufficient.

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 uses a specific verb 'Fetch' and identifies the resource as 'a document or backtest result' retrieved by id, linking the id source to 'search'. It is clear about what the tool does, though it does not explicitly differentiate itself from the sibling tool 'get_backtest'.

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 'as returned by search' implies that this tool is meant to retrieve items that were previously found via search, which is useful context. However, no explicit when-to-use or when-not-to-use guidance is provided relative to alternatives like 'get_backtest' or 'list_backtests'.

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