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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds genuine context beyond that: the fact that it covers 'every Medicare facility' the owner controls, the sector scope, and the PE/REIT flagging, which tells the agent what kind of intelligence it will get back.

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?

Two sentences: the first front-loads the purpose and the returned signal set, the second carries the input prerequisite. No filler, no restatement of the title, and the parenthetical endpoint reference is the only detail an agent actually needs to source the id.

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, yet the description compensates by naming the concrete return fields (facility_count, per-sector breakdown, PE/REIT flags, state spread). With one required parameter fully documented and the annotations covering safety, nothing needed to invoke 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% for the single parameter, and the schema already says 'Numeric CMS owner associate id', so baseline is 3. The description goes further by identifying the provenance of that id (the largest-owners and private-equity endpoints) and constraining it to a single organization owner, which reduces the risk of passing a person-level or facility-level id.

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 ('Trace one organization owner across every Medicare facility it controls') and enumerates the sectors covered (hospital/hospice/home-health/skilled-nursing). An agent can immediately distinguish this owner-centric rollup from facility-search siblings such as epa_facilities or building_permits_search.

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?

The description supplies the operative precondition — the tool 'takes a CMS owner_associate_id' — and names the endpoints that produce that id (/api/v1/owners/largest, /owners/private-equity), routing the agent to the right upstream data. It does not state when NOT to use this tool or name a competing sibling, so it falls short of 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.