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

Annotations provide only `destructiveHint: true`, so the description carries most of the burden; it adds the useful API mapping 'sevdesk: POST /Contact' but says nothing about permissions, duplicate handling, or whether the call is idempotent. For a write tool with minimal annotation coverage this is adequate but shallow.

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 core action, then the field-shape rule, then the sibling hand-off and endpoint. No filler and nothing buried.

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 the create semantics and the address/email hand-off, but for a tool with no output schema the description never indicates what comes back (e.g. the new contact id), which an agent needs in order to chain into `sevdesk_add_communication_way`. No mention of failure modes or the required `category_id` beyond what the schema already states.

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%, so the schema already documents all 11 parameters including the category_id codes and the name/surename/familyname person-vs-organisation rule. The description restates that rule in condensed form, which helps agents that skim, but adds no syntax, format, or validation detail beyond the schema. 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 ('Create a contact') and immediately branches on the two mutually exclusive shapes (organisation via `name`, person via `surename`/`familyname`). It also names the sibling `sevdesk_add_communication_way` as the place for addresses and emails, so an agent can separate create-contact from create-communication-way without opening schemas.

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 clear positive guidance on which fields to supply and routes the address/email sub-case to a named alternative. It lacks an explicit 'when not to use' (e.g. an existing contact should go to `sevdesk_update_contact`), but the create-vs-update distinction is self-evident from the verb.

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