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

With no annotations, the description carries the full behavioral burden, yet it discloses nothing about pagination, result volume, permissions, or what a period filter does to results. 'Rows' hints at a tabular return but the scope and limits are unstated.

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?

A single compact sentence with no filler; the resource and keys are front-loaded. It is arguably too terse for the tool's complexity, but there is no wasted wording.

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?

All three parameters are optional, so an agent needs to know what happens when cik, cusip, or period are omitted, and how large the returned row set can be. With no annotations and no output schema, the description should cover these gaps and does not.

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% (cik, cusip, period all documented in-schema), so the baseline is 3. The description confirms cik and cusip are the selection keys but adds no format or precedence detail beyond the schema.

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?

Identifies the resource ('13F holdings rows') and the two lookup keys (CUSIP, filer CIK), which lets an agent place it among filing-related siblings. However, there is no verb and no indication of whether it returns a list, a summary, or a single record, so the purpose is only partially pinned down.

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 names the two query keys but never states when to use this tool versus related siblings like structured_form, search_filings, or company_facts. No prerequisites, no exclusions, no alternative routing.

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