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

Annotations already mark the tool read-only and idempotent; the description adds genuinely valuable behavior beyond those hints: 404 behavior with error code, flat 30-credit charge even on 404, null quarter-over-quarter fields for the earliest quarter, response layout, and EDGAR URL semantics. No contradiction with annotations.

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 longer than average but front-loaded with the core purpose and each section adds operational value: anchoring, response shape, null behavior, cost, and endpoint. The endpoint path and documentation file reference are slightly redundant, but not enough to hurt usability.

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 correctly carries the burden of explaining return values: top-level manager fields, per-quarter row fields, and null behavior for the earliest quarter. It also covers error behavior, cost, and sort default, leaving the agent with what it needs to select and call the tool 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 adds useful extra meaning for cik/name by explaining that an ambiguous name causes a 404 and recommending CIK as the reliable anchor, and it reinforces sort_order's newest-first default. Page and page_size semantics are left to the schema, but the additional guidance raises the score.

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 opens with a specific verb and resource: 'One institutional manager's 13F history' and explicitly contrasts its scope with search_institutional_holdings ('the same quarter rows ... for one manager'). It is not a tautology and clearly differentiates this tool from its sibling.

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 gives clear operational guidance: anchor with exactly one of cik/name, query by CIK because several managers can share similar names, and expect 404 when no single manager matches. It references search_institutional_holdings as the row-format source, though it stops short of explicitly saying 'use search_institutional_holdings when you need multiple managers.'

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