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

Annotations only cover readOnlyHint and openWorldHint, and the description adds substantial beyond that: a 500-row cap, ≤10 req/s EDGAR limit, public-domain source, and a full pricing model ($0.004 USDC per successful call via x402, failed calls not charged). That is exactly the behavioral context annotations cannot provide.

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 purpose, then return shape, then constraints and cost. Every sentence is informative, though explaining return fields is partly redundant given an output schema exists.

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 an external, paid, rate-limited data tool it covers purpose, inputs, output shape, row cap, source, rate limit, and billing, which is everything an agent needs to call it correctly. The presence of an output schema means return values need not be spelled out, making coverage more than sufficient.

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 all three parameters are already documented in the schema, including that name is used when cik is absent and the 1–500 limit range. The description largely echoes this, so the baseline of 3 is appropriate.

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 names a specific verb and resource ('Returns the latest Form 13F-HR holdings for an institutional investor'), which is clearly distinct from generic filing tools. It does not, however, explicitly name any sibling (e.g. sec_filings, sec_insiders) to differentiate itself, so it lands at a clear-but-not-routing 4.

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 signals the two input modes ('by CIK or name search') and that name is used when CIK is absent, implying when each applies. But it never states when to reach for this tool versus the many other SEC siblings, leaving usage context to inference.

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