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

Annotations already mark the call read-only and idempotent; the description adds non-obvious behavioral context: flat 148-credit cost, endpoint path, Starter plan requirement, formula_override requiring Pro+, and light_weight_mode's payload-reducing effect. No contradiction with 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?

The most important contrast (filing-date-only vs realtime sibling) is front-loaded, and the remaining sentences each carry operational facts: use cases, cost, optional payload flag, endpoint/docs, and auth tiers. It is dense without being padded.

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?

Together with the fully documented schema, the description is sufficient for selecting and calling the tool. It doesn't spell out the exact return shape, but the 'same 13 valuation ratios as get_valuation_metrics' reference supplies that context via the sibling.

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 already covers 100% of parameters with clear descriptions, so baseline is 3. The description adds value beyond the schema by explaining plan gating on formula_override and clarifying that current_price/current_fx_rate are not accepted in this variant.

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-resource pair and immediately distinguishes this tool from get_valuation_metrics: same 13 ratios but filing-date only, with no realtime computation or current_price/current_fx_rate. This makes the tool's identity and boundary unambiguous.

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?

It states exactly when to use it (historical filing-date snapshot, analyzing past filings, batch loads), explicitly excludes realtime computation, and names the sibling alternative it differs from. This is explicit when/when-not/alternative guidance.

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