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

With no annotations, the description carries the full burden and does so well: it discloses text processing (HTML/iXBRL stripped, tables tab-separated), truncation and paging behavior via max_chars/offset, the data source, and that errors are not charged. It omits details on the x402 payment flow mechanics and rate limits, leaving modest gaps for a paid mutation-free read tool.

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 description is a single dense paragraph that front-loads the purpose and then layers output, parameters, data source, and pricing. It is mostly efficient, though it repeats schema defaults like max_chars values and offset defaults, which are already documented in the schema.

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, so the description must explain return values, and it does so thoroughly: form, filing date, company, total_chars, a text window, and the list of all documents. Combined with error-charge policy and data source, an agent has everything needed to call and interpret the tool.

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 baseline is 3. The description adds meaning by explaining the offset/next_offset paging relationship, the default primary-document behavior of the document parameter, and the rationale for company (needed when a filing agent submitted the filing), which goes beyond the schema's field-level text.

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 and resource: 'Fetch one document of an SEC filing by accession number and return clean plain text'. It further scopes the tool by explaining the default (primary document) versus exhibits, which distinguishes it clearly from sibling tools like recent_filings and company_facts.

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?

The description gives clear usage context, including when to target an exhibit (EX-99.1 earnings release) and when to pass the company parameter (filing agent submissions). It does not explicitly name alternatives or state exclusions relative to siblings, but the context is sufficiently clear for correct invocation.

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