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

Annotations only give readOnlyHint=false, openWorldHint=true, idempotentHint=false. The description adds the crucial behavioral facts: every call is PAID in USDC from a configured wallet, spend is bounded by budget caps, results are third-party data (not instructions), and a free preview path exists. That is exactly the extra context the annotations cannot convey.

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?

Front-loaded correctly: purpose first, payment model second, free alternative third, product catalogue last. It is long but the length is driven by 13 real products, and some entries are visibly truncated ('8-K items with...', 'rev...'), which is slightly sloppy but not wasteful.

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 13-product multiplexer with no output schema, the description covers purpose, cost, budget behavior, per-product params, and a free alternative. It stops short of explaining result shapes or how budget-cap failures surface beyond what the schema's confirm_over_cap field already says.

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?

Although the three top-level schema properties are fully described, the nested `params` object is `additionalProperties: true` with no schema-defined keys. The description supplies the entire per-product parameter vocabulary (ticker, cik, accession*, q*, limit, id, etc.), marks required params with '*', and states each product's price — meaning well beyond the schema.

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 opening sentence names a specific resource — 'Company records: US SEC EDGAR ... and national company registers' — and the product list makes the exact scope unambiguous against siblings like court_opinions or patent_lookup. An agent can tell what this tool covers without opening the 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?

It gives clear selection guidance within the tool ('Pick the product for the country') and names a real alternative route ('free_sample shows a real answer of this product for free'). It does not say when to prefer this tool over generic siblings like call_product or list_products, so exclusions are missing.

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