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

Annotations already declare readOnly, idempotent, non-destructive, open-world, so the safety profile is covered. The description adds real behavioral context beyond them: results are ordered newest first, and each row carries the issuer, holder(s), voting-rights % incl. instruments, shares %, reason, and a per-row source credit.

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 dense sentence that front-loads the resource, scope, and output fields, then ends with the filtering and prerequisite pointer. Every clause carries information, though the packing of returned fields makes it slightly heavy to parse.

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?

Output schema exists, so return values need not be explained, and annotations cover the safety profile; the description still supplies the market scope, filtering, ordering, and a prerequisite tool reference. Nothing needed to call this correctly is missing.

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 page, limit, issuer, and country are already documented, including the issuer-id grammar and the country values. The description's 'Filter by issuer id' and market list only restate the schema, adding no syntax or behavioral detail beyond it.

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?

Specific verb+resource: 'European major holdings (voting-rights) notifications', with the covered markets (Sweden, Netherlands, Denmark, UK) and sort order spelled out. This cleanly separates it from siblings such as get_eu_insider_dealings and get_eu_short_positions, which are different EU disclosure regimes.

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?

Gives concrete usage context: 'Filter by issuer id' and routes to get_eu_markets to determine which markets are live before calling. Clear when-to-use, but there are no explicit when-not-to-use statements or comparison against the closest sibling (e.g. insider dealings vs. holdings).

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