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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=true and openWorldHint=true. The description's real contribution is the PATCH semantics ('only the fields you pass are changed'), which meaningfully lowers the agent's fear of clobbering untouched fields. It never addresses the destructiveHint flag (e.g., whether empty strings clear values) or error behavior on an invalid id, so it adds context but stays mid-range.

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, front-loaded with the 'WRITE:' modality marker, then the semantics, then the prerequisite. Nothing is wasted and the mutating nature is the first thing read.

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 15-parameter mutation with no output schema, the definition covers modality, partial-update behavior, and read-before-write. Remaining gap is field-clearing behavior and validation failure handling, which matters given destructiveHint=true, but it is otherwise sufficient to call 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 description coverage is 100% across all 15 parameters, with enums documented for contact_type and delivery_method, so the schema carries the load. The description adds only the partial-update contract, not per-field semantics. 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+resource ('change fields of an existing contact') and adds the crucial detail that it is a partial update ('only the fields you pass are changed'). 'Existing' implicitly separates it from papierkram_create_company, though no sibling is named explicitly for that contrast.

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?

Gives an explicit prerequisite: read the record first with papierkram_get_company, which tells the agent the correct call sequence. It does not state exclusions (e.g., use create_company for new records), so 4 rather than 5.

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