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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so safety is covered and the description should not be penalized for restating 'Read-only'. It adds genuinely new behavioral context: the 1-unit cost limit and the fact that stored decisions and links are retrieved, not just today's verdict. It stops short of describing auth requirements or whether stored decisions persist beyond the call.

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 cleanly labeled Use/Inputs/Returns/Limits blocks with no wasted prose. The Returns enumeration is slightly redundant given a full output schema, which keeps it just short of a 5.

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?

Covers purpose, sequencing, parameter identification, return shape and cost in a compact space. With an output schema present the Returns line is bonus rather than a gap, so nothing an agent needs to invoke the 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 coverage is 100% and both parameters already carry descriptions and examples ('A Fuentio record ID', 'Another record ID'). The description's 'Inputs: left and right, Fuentio record IDs' with the same example strings largely duplicates the schema, so this sits at the baseline rather than adding new meaning such as ordering effects or type/format constraints.

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?

Specific verb (explain) plus a precisely scoped resource (whether two register records are the same company), naming exactly what is returned: today's decision, reason codes, evidence, stored decisions, links, and shared-entity status. An agent can distinguish it from resolve_company and the other check_/verify_ siblings without opening any 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?

Explicit sequencing ('Use it after resolve_company or lookup_company') and an explicit exclusion with the alternative named ('Don't use it to find companies: call resolve_company'). Both the when and the when-not are stated with the redirect target.

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