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

The only annotation is destructiveHint=true, so the description carries most of the burden and does add value: it discloses the outbound email side effect, that it is on by default, and how to suppress it. It is consistent with destructiveHint (record creation + external email). It stops short of saying what happens on duplicate emails, what permissions are needed, or what is returned.

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 short sentences plus the endpoint mapping; the default-vs-silent behavior is front-loaded and no sentence is padding. Efficient and easy to scan.

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 five-parameter create tool with no output schema and only a single annotation, the description covers the invitation behavior but says nothing about the result (e.g., whether the new customer id is returned), duplicate-email handling, or required permissions. Adequate to invoke, but not fully complete for an agent that needs to chain the created record into later calls.

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%, with all five parameters documented in the schema, so the baseline is 3. The description restates the send_invitation_email toggle (already in the schema as 'TeamUp default: true') and links email to the invitation, adding only marginal meaning beyond structured fields.

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 ('Add a new customer to the business as staff') plus the underlying endpoint (POST /customers), which is enough to distinguish it from goteamup_get_customer, goteamup_list_customers, and goteamup_register_customer_for_event without opening the schema. The 'as staff' qualifier even clarifies what kind of customer record is produced.

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 operational context: by default an invitation email goes out, and setting send_invitation_email=false adds the customer silently. That is real when-to-use guidance for the tool's main branch point. It does not, however, say when to prefer this over siblings like goteamup_register_customer_for_event, nor note any prerequisites/exclusions.

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