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

With only readOnlyHint=true in annotations, the description carries real behavioral load: it discloses the silent truncation to the first 10 unique tickers, the counterintuitive rule that a missing metric FAILS its criterion, the returned shape, and that caveats ride tool_notes. These are non-obvious traits an agent could not infer from the schema or annotations.

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?

Dense but front-loaded: the core mechanics (scope, cap, missing-metric rule, return shape) come first, with the disclaimers trailing. It is slightly packed with caveats, but for a screener with 8 params and non-obvious semantics, each 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?

No output schema exists, but the description compensates by enumerating the return envelope (summary, count, passing_count, criteria, results, as_of) and per-result fields, plus the data source and caveat location. Complete enough to call correctly, though it does not explain how empty/invalid tickers are surfaced.

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 coverage is 100%, so the schema already documents each parameter, giving a baseline of 3. The description adds units semantics beyond the schema ('whole USD; *_pct as percentage numbers'), clarifying that percent params are passed as plain numbers rather than fractions.

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 (threshold screen) and resource (latest-year SEC EDGAR XBRL fundamentals) with explicit scope (caller-supplied ticker set). It also distinguishes itself from siblings by stating 'It never sweeps a universe and is not a discovery screen,' separating it from get_fundamentals-style lookups and discovery tools.

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?

Gives clear when-not guidance: not a discovery screen, not a universe sweep, and explicitly not a buy signal. However, it never names the sibling an agent should use instead for discovery or single-name lookups, so the alternative routing is left implicit.

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