get_holders

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

Annotations already cover safety (readOnlyHint=true, openWorldHint=true), so the bar is lower. The description adds genuine behavioral context: the failure mode for non-equity symbols and the shape of the returned data. It does not mention pagination or limits on the summary section, which would be the remaining gap.

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?

Three tight sentences: the core purpose first, the return contents second, the equity-only restriction last. No filler, no restatement of the name.

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, the description needn't explain return values, yet it still gives a useful preview of the payload. Combined with the equity-only constraint, an agent has enough to decide and call correctly; only the alternative routing for non-equity symbols is unstated.

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% – both 'symbol' and 'limit' are fully documented in the schema, including ticker/ISIN formats and the 1–100 range. The description adds no parameter-level detail beyond that, 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?

States a specific verb and resource ('Get the ownership breakdown for a Yahoo symbol') and enumerates the payload ('insider/institutional percentages plus the top institutional and mutual-fund holders'). This clearly separates it from siblings like get_insider_activity, get_shares, and get_fund_data.

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?

Explicitly scopes applicability: 'Equity-only: an ETF, fund or crypto symbol answers with an error that says so.' That is a real when-not condition an agent can act on. It stops short of naming which sibling to call instead (e.g. get_fund_data for funds), so it is not a full 5.

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