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

Beyond the annotations (which already declare read-only, idempotent, non-destructive, closed-world), the description discloses genuinely non-obvious behavior: person owners appear only where person data is enabled, chains otherwise terminate with a stated terminal reason, and hop values are served verbatim rather than synthesized. This is exactly the added context annotations cannot carry.

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 parameters, then conditional behavior, with no filler. The final sentence about include_persons is dense and slightly overloaded, but every sentence carries 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 does the heavy lifting on return shape: chains cited hop by hop, per-register coverage notes, and terminal reasons. It is nearly complete, only undercut by the dangling include_persons reference that the schema does not back up.

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 node_id, threshold and max_depth semantics are already fully documented in the schema; the description largely restates defaults (25, max 8). It references 'params.include_persons,' which does not exist in the input schema — a minor confusion source that offsets the otherwise solid node_id provenance note.

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?

The opening sentence gives a specific verb+resource: 'upward ownership chains of one company, composed across registers and cited hop by hop.' An agent knows exactly what it retrieves, though it never names a sibling (company_network, company_profile) to contrast against, so differentiation is implied rather than stated.

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?

Usage is implied rather than stated: the description notes node_id comes from search_companies hits and warns it is 'not the entity_id of company_profile,' which is a useful routing hint. However, there is no explicit when-to-use/when-not guidance or a named alternative for retrieving ownership structure instead.

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