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

Goes well past the annotations: ordering (largest first), recency semantics of 13F filings, and an unusually explicit cost model (first 25 free, $0.01/call via x402 or card key, failed calls free, repeats are not free). The annotations already declare readOnly/non-destructive, and the description reinforces 'reads or computes only and changes nothing'.

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-loads what the tool returns and how to identify the filer, then pricing at the end where it belongs. The final billing sentence is a long run-on that packs in several clauses, but each sentence carries information the agent needs.

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 cover return shape, and it does: issuer, class, CUSIP, USD value, shares, portfolio weight, report period, total value and position count. Combined with the pricing and freshness notes, an agent has everything needed to call it correctly.

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 restates the filer-vs-CIK choice already documented in the schema and omits the limit parameter entirely, adding no syntax or format detail beyond what structured fields provide.

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: 'latest 13F-HR holdings of an institutional investment manager ... from SEC EDGAR', and enumerates the returned fields. Naming the 13F-HR form cleanly separates it from sibling tools like sec_filings, sec_8k and sec_insider without the agent having to open a 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?

'Use to see what a fund owns' plus a worked example (filer=Berkshire Hathaway) gives a clear trigger. It also supplies timing context (filed quarterly, up to 45 days after quarter end) that tells the agent when data may be stale. It never names an alternative or an exclusion, so it stops short of a 5.

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