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

Goes well past the idempotentHint/destructiveHint annotations by disclosing the read-modify-write implementation, the fact that the API requires name on every update, that unpassed fields retain values, and that passed fields are overwritten. That is exactly the mutation behavior an agent needs before invoking.

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: purpose, then semantics of the merge, then the underlying endpoint. No filler, and the most decision-relevant fact (unpassed fields survive) is front-loaded.

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?

For a 25-parameter mutation tool with no output schema, the description supplies the missing behavioral contract: partial update semantics, the name requirement, and destructive scope. Nothing essential to invoking it 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?

With only 48% schema description coverage across 25 parameters, the description carries real weight: it explains that name must effectively be supplied on every update even though the schema lists only id as required, and that omitted fields are preserved. Many of the remaining 25 fields (city, iban, address) are self-evident, but the partial-update contract is a meaningful addition.

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 ("Change fields of an existing relation") and names the endpoint (GET + PATCH /v1/relation/{id}), which the siblings create_relation/get_relation/list_relations do not. It implicitly separates itself from creation by saying "existing relation", but never names those siblings explicitly.

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?

It gives clear context for the partial-update case (fields not passed keep their values), but offers no explicit when-to-use/when-not guidance and never routes the agent to create_relation for new records or get_relation for reads. Usage is implied rather than instructed.

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