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

Annotations only carry destructiveHint=true and a title; the description adds real behavioral context beyond that – it is a WRITE, it is a one-shot request that should not be blindly retried, and the result should be checked. This non-idempotency disclosure is valuable. It stops short of stating permission/auth requirements, so not a full 5.

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-loaded with the WRITE warning and every sentence carries information: write scope, retry behavior, required-field rule, duplicate-avoidance workflow. The trailing 'POST /person/create.json' is mildly redundant but harmless.

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 an 11-parameter write tool with 100% schema coverage and no output schema, the description covers mutation nature, non-idempotency, the default-required fields, and duplicate prevention. Auth/permission expectations are the only notable gap.

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 baseline would be 3, but the description adds a constraint the schema does not encode: 'Give company, first_name or last_name (at least one),' since the schema declares zero required parameters. That materially changes how the agent fills the payload.

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?

The description opens with a specific verb ('Creates') and resource ('a customer, vendor or other contact'), which maps cleanly to the person resource. It distinguishes itself from the read siblings by explicitly naming cashctrl_list_persons as the search-first alternative.

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 a concrete when-to-use workflow: 'Search first with cashctrl_list_persons so no duplicate is created,' and a retry rule: 'check the result before trying again.' Both the alternative tool and the condition selecting it are explicit.

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