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

Annotations already cover the safety profile (readOnly=false, destructive=false, idempotent=false, openWorld=true). The description adds genuine context beyond that: the required permission scope ('Needs contacts.write') and the side-effect boundary that no company link is created.

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 short sentences, front-loaded with the WRITE marker and the entity identity. Every clause carries information; nothing is redundant padding.

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 9-parameter creation tool with no output schema and thin schema coverage, the definition is minimally viable: it establishes the write nature and permission, but omits what the call returns (e.g. the new contact id) and how to subsequently associate the contact with a company.

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 9 parameters and only 33% schema description coverage, the description carries a real compensation burden but mentions no parameters at all — not even which fields drive duplicate matching (e.g. email) or what civility/owner_id mean. The undocumented fields remain opaque from both sources.

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 ('create a contact (a person) in Sellsy') and clarifies the object type, which helps separate it from sellsy_create_company. It does not explicitly differentiate from sellsy_create_individual, the closest ambiguous sibling, leaving the agent to infer that distinction.

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 is not linked to a company by this call' implies a usage context (standalone person record), but the description never states when to pick this over sellsy_create_individual or sellsy_create_company, nor what call to make to attach a company afterwards.

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