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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful context beyond the annotations: 'Credential-free public SEC data,' which tells the agent no authentication is needed, plus what the response contains (metadata and primary document URL). It stops short of richer traits like rate limits or pagination, so a 4.

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?

Three short sentences, each earning its place, with the return value and input requirement front-loaded before the routing hint to the sibling tool. Zero waste.

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?

An output schema exists, so the description needn't explain return fields, and the annotations carry the safety profile. For a read-only lookup tool, nothing an agent needs to call it correctly 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 coverage is 100%, so the baseline is 3, but the description adds the required-vs-alternative relationship: accession is required, with cik or ticker as the positional identifier ('accession plus cik or ticker'). This helps the agent compose a valid call rather than just reading individual field docs.

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 ('Returns a single SEC filing's metadata and primary document URL'), and explicitly distinguishes itself from the sibling sec_filing_sections by naming it. An agent can tell exactly what this returns versus the section-extraction tool.

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?

Names the alternative ('sec_filing_sections to extract 10-K/10-Q/8-K item sections') and the condition that selects it, and states the input requirement ('Provide accession plus cik or ticker'). Nothing is left to inference about when to use this vs the sibling.

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