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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), and the description adds real context beyond them: the SML→SMP resolution path, that the SMP ServiceGroup is the authoritative check, keyless/no-membership access, and the registered=false-with-reason failure mode. Return-format detail is partial but useful.

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-loads the purpose, then mechanism, then failure behavior, then routing advice. Dense with technical detail (SML/BDXL/SMP ServiceGroup) but every sentence earns its place; no redundancy with the schema.

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, so the description carries the return burden and does so adequately (registration status, accepted document types, registered=false with reason). Combined with the correct alternative routing, an agent has enough to call this correctly.

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%, so the schema already documents scheme, environment, and the participantId format including the ICD-code requirement. The description reinforces the identifier-vs-name distinction but adds no syntax or format detail beyond what the schema provides — 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: 'Check whether a company is registered on the Peppol e-invoicing network and list every document type it accepts.' It also distinguishes itself from search_participants by name and explains the registration-check role, so an agent can route without opening the 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?

Explicitly names the alternative and the selecting condition: 'Use search_participants first if you have a company name rather than an identifier.' It also clarifies prerequisites (keyless, no Peppol membership needed), though it does not contrast against the adjacent get_participant_endpoint sibling.

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