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

Annotations already declare readOnlyHint=true, openWorldHint=false, destructiveHint=false, so safety is covered. The description adds real behavioral value beyond that: shares are restated onto today's split basis, the change is computed against the filer's previous 13D/13G, results are ordered largest block first, and reporting persons on one filing must not be summed. Pagination behavior for offset/maxResults is left to the schema.

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 purpose is front-loaded in the opening clause and the trailing sentences carry high-value caveats rather than filler. The field enumeration is dense but every clause names a returned attribute, so little could be cut without losing information.

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 return-value burden and does so thoroughly – listing the per-filer fields and the cover-page reporting-person fields. The only gaps are pagination/result-count behavior, which the schema already covers, and no explicit note on empty results when a ticker has no 13D/13G filings.

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% – ticker, offset, and maxResults are each documented in the schema, including the 1-500 clamp and default. The description adds no parameter syntax, format, or edge-case meaning beyond what the schema already provides, so the 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?

The description names a specific resource (Schedule 13D/13G beneficial-ownership records for a stock or ETF listing) and enumerates the exact payload: filer, event date, split-adjusted block, percent of class, change since prior filing, and cover-page reporting persons. This clearly separates it from sibling 13F/insider tools such as GetInsiderOwnership, GetInstitutionalOwnershipHistory, and GetTopHolders.

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?

Usage is implied rather than stated: an agent can infer you call it with a ticker to see 13D/13G filers, and the 'never add them together' rule is genuinely useful interpretation guidance. However, no sibling alternative is named and no when-not condition is given, so the agent must still decide on its own between this and the various other ownership tools.

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