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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is low. The description still adds real context: the catalog size (325 ratios) and that the return value is the exact ratio names screen_stocks accepts, which tells the agent what it gets back and why it matters.

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?

Two sentences, zero filler, with the core action and both invocation modes front-loaded before the return-value note. Every clause earns its place.

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?

There is no output schema, but the description compensates by stating what comes back (exact ratio names accepted by screen_stocks) and the catalog size. For a one-parameter lookup tool that is entirely 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?

With a single optional parameter at 100% schema description coverage, the schema already documents 'q' fully. The description's keyword examples ('cash flow', 'debt', 'promoter') largely restate the schema's examples, so it adds little meaning beyond syntax already present.

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?

States a specific verb+resource ('Search or list available financial ratios') and names its consumer, the screen_stocks tool, which no sibling shares. An agent can immediately tell this is a discovery helper for valid screen field names rather than a data-fetch tool.

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?

Explicitly describes both modes: pass a keyword to search, omit for the full catalog, and frames the purpose as finding names that screen_stocks accepts. It gives clear context and an implicit when-to-use (before constructing a screen), though it does not state exclusions or name an alternative lookup path.

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