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

Annotations already declare read-only, idempotent, non-destructive, open-world behavior, so the safety profile is covered. The description adds genuinely non-structured traits: results are sorted newest first, rows carry a per-row source credit, and the link to the original report is only present 'where the source allows' — a real caveat about inconsistent output.

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-loads the resource and markets before the operational details, and every clause carries information (ordering, fields, caveat, filter, sibling pointer). It is dense and slightly run-on in the middle, but there is no filler.

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 an output schema present, return values need no explanation, and the description still covers scope, ordering, filtering, and where to check market availability. Nothing an agent needs to invoke this filtered-list tool 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 all four parameters (page, limit, issuer, country) are already documented in the schema, including the issuer id format and country codes. The description's 'filter by issuer id' adds emphasis but no syntax or semantics beyond what the schema provides, making the baseline 3 correct.

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?

Names the specific resource (European annual financial report filings), the four covered markets, the sort order, and the columns returned. It is clearly distinguishable from siblings like get_eu_insider_dealings or get_eu_major_holdings without opening a 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?

Gives clear operating context: filter by issuer id, and route to get_eu_markets to learn which markets are live. It stops short of stating when this tool should NOT be used versus other EU filing tools, so it is strong context rather than full when/when-not guidance.

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