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

Goes well beyond the annotations, which only declare readOnlyHint=false, destructiveHint=false, openWorldHint=true. The description adds that nothing is sent to the person, that the operation is reversible from within SignUpGenius, that it accepts one person per call, that it returns the member ID, and that a Cotlet API key with app access is required — exactly the kind of side-effect and auth context an agent needs.

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-loads the purpose well, but several sentences restate the same idea: 'Sends nothing' is repeated as 'Nothing is sent to them,' and 'Add a person to one of your groups' is echoed by 'Adds one person to a group.' This redundancy costs some efficiency.

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 4-parameter write tool with no output schema, the description covers purpose, side effects, reversibility, call granularity, return value, and auth requirements. It is essentially complete, with only minor redundancy keeping it from a 5.

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 email, group_id, first_name, and last_name, including the 'Group ID from list_groups' cue. The description mentions 'one person per call' and 'returns the member ID' but adds no field-level syntax or format detail, so the 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: 'Add a person to one of your groups,' and clarifies the intent ('so you can invite them later'). It implicitly distinguishes from sibling add_participant (participants vs. group members) by phrasing and by referencing list_groups in the schema, though it never names a sibling explicitly.

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 a clear usage context ('so you can invite them later') and behavioral preconditions ('runs without asking first' since it is non-destructive and reversible). It stops short of explicitly stating when NOT to use it or naming alternatives like add_participant, so it is short of a 5.

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