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

Annotations only cover readOnlyHint and openWorldHint, but the description adds the commercially critical facts an agent must know before calling: $0.003 USDC per successful call, x402 payment rails (Base, Solana, Arc), and that failed calls are not charged. It also discloses the result cap and the extraction limitation, which annotations do not 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 with the core operation, then constraint, then cost, which is the right order for scanning. The enumeration of return fields (company name, CIK, form type, date, link) partially duplicates the output schema and could be trimmed without loss.

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 4-parameter, single-required-arg search tool with full schema coverage and an output schema, the description covers purpose, coverage limits, cost and billing semantics, and result ceiling. Nothing an agent needs before invoking it is missing.

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 description coverage is 100%, so q, days, form and limit are already fully documented with ranges and defaults. The description restates the optional form/date narrowing and the 10-result cap but adds no syntax, format, or edge-case detail beyond the schema. Baseline 3 applies.

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 and resource ("Full-text search of US SEC EDGAR filings") plus the source index ("SEC public index"), and lists exactly what comes back (company name, CIK, form type, filing date, filing index link). No sibling covers SEC EDGAR, so the tool is unambiguous within the catalog.

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 a clear when-to-use boundary by naming the negative case: "Full-text only: no financial figures are extracted," which tells an agent not to route numeric/statement questions here. It also notes the optional narrowing dimensions (form type, date range) and the 10-result ceiling. It stops short of naming an alternative tool for the financial-figure case.

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