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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds real value beyond that: results are split into equity holdings and debt holdings, each weight is the issuer-published figure, and each carries the filing date of that book — useful freshness context. No pagination or ordering-limits behavior is described, which keeps it below a 5.

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 core purpose, then use cases, then return shape — a sensible order. Slightly padded by restating the same idea as both prose and example questions, but every sentence still conveys scope or output 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?

With no output schema, the description must describe returns, and it does: fund list, issuer-published weight, filing date, plus a separate debt-holder section. The only real gap is the undocumented 'limit' parameter and any ordering/cap behavior.

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 0%, so the description must carry both parameters. It does well on 'company' ('takes a company name or its ticker') and adds a coverage stat (31,019 companies), but the 'limit' parameter is never mentioned in either the schema or the description, leaving half the surface undocumented.

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 and resource — 'which US listed ETFs hold a given company, ranked by how much of each fund it is' — which is precise and immediately usable. It also pins the direction of the relationship ('X is a company rather than a fund'), which implicitly separates it from the reverse-lookup sibling etf_holdings.

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 triggering questions ('which ETFs hold X', 'which fund holds the most X', 'how do I get exposure to X') and an explicit scope exclusion (company, not fund; also covers debt/bond holdings). It does not name the alternative sibling tools by name, so routing is by inference rather than explicit direction.

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