Recent activist hedge-fund stakes (SEC Schedule 13D)

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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial context beyond them: the sort order (newest first, then stated-intent strength), the per-row payload (filing_url and a 600-char item4_excerpt quoted as data), and two real behavioral caveats (13G excluded, filings lacking a source link dropped).

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 the 'Use when' trigger, then scope, then return shape, then caveats in a logical order with zero filler. It is dense but every clause carries information, with only slight length pressure from the item4_excerpt parenthetical.

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?

With no output schema, the description must describe return values and it does: sort order, per-row fields, excerpt cap, and drop/coverage rules. Combined with 100% schema coverage and safety annotations, an agent has everything needed to call and interpret this 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 description coverage is 100%, so the schema already documents all five parameters including pagination and limit semantics. The description only names three filters (ticker, min_percent, days) that 'narrow' results, adding no syntax or edge-case detail beyond the schema. Baseline 3 applies.

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 (returns) and resource (activist Schedule 13D/13D-A filings on US-listed companies), and pins the domain precisely enough to be distinguished from the passive-13G world it explicitly excludes. An agent can tell what this returns without opening the 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?

Opens with an explicit trigger ('Use when the user asks about activist investors, hedge-fund stakes, or recent 13D filings') and gives an exclusion (passive 13G is not covered). It does not name the sibling verify_activist_13d as the alternative for verification, so routing to the closest sibling is left to inference.

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