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

With no annotations present, the description carries the full disclosure burden and largely meets it: it reveals the read-only nature (metadata only), the response fields, keyset paging via next_cursor, and the negative space (no performance data). A 5 would require additional operational traits such as result ordering or rate-limit behavior, which remain implicit.

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?

Four tight sentences, each earning its place: the core purpose is front-loaded, followed by the response summary, the pagination note, and the explicit routing to sibling tools. There is no filler or redundant repetition of what the schema already states.

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?

Without an output schema and annotations, the description must explain return values and behavioral boundaries, and it does: result fields, pagination, and the exclusion boundary are covered, while the nested schema documents the remaining input details. The only completeness gap is the absence of operational details like rate limits or result ordering.

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?

Top-level schema coverage is 0%, so the description must compensate, and it partially does: it gives `q` its purpose (search by name/ticker to obtain the code), states the type values ETF/FUND, and explains the cursor round-trip. However, `limit`, `country`, and `exchange` are not mentioned in prose; the nested schema documents them clearly, so the practical gap is moderate.

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 opens with a specific verb and resource: 'Search the ~32,000 US mutual funds and ETFs by name or ticker' to obtain the `code` other tools need. It also differentiates from siblings by stating what it returns (metadata only) and what it does not (performance figures), so an agent can tell it apart from getTrailingReturns and getCalendarReturns without opening a schema.

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 positions the tool as the necessary lookup step — 'to get the `code` the other tools need' — and explicitly names the alternatives for the excluded functionality: 'No performance figures here; use getTrailingReturns / getCalendarReturns for those.' This is precise when-to-use guidance that leaves nothing to inference.

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