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

The description discloses substantial non-obvious behavior beyond the annotations: portfolio value excludes options, changes and sold-out positions are omitted if the prior quarter was not filed, ticker-less securities have null URLs, and the hard cap of 200 holdings with pagination. This is exactly the kind of context that helps the agent anticipate results.

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 dense single paragraph, but nearly every clause carries distinct information and there is no filler. It is front-loaded with the core resource, though its run-on structure prevents it from being a model of concise clarity.

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 a tool with this complexity, the description covers all major output areas: identity, quarter history, holdings, changes, sold-out positions, options, valuation edge cases, and pagination. The output schema still exists to carry formal return structure, but the description leaves no major practical gap.

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%, which sets a baseline of 3. The description adds meaningful behavior around the quarter parameter (defaults to latest filed quarter) and clarifies pagination/output semantics like pct_of_portfolio and share change, so it earns one point above baseline.

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 states a specific verb-resource relationship: it retrieves one 13F filer by SEC CIK and details the names, quarters, holdings, sold-out positions, and options. It is clear and specific, but it does not explicitly contrast this tool with siblings like get_stock_13f_holders or get_superinvestor_activity, so it stops short of a 5.

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 no guidance on when to choose this tool over alternatives or when not to use it. It mentions defaults and a pagination instruction ('use page'), but that is operational details, not usage context or exclusions.

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