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

Annotations already declare a non-read-only, non-destructive, non-idempotent mutation; the description adds the real constraint an agent needs — the only legitimate data source is the human's own statement — plus an explicit effect statement ('attendance recorded on the event'). It stops short of saying what happens on re-recording an already-set attendance or what the call returns, which matters given idempotentHint=false.

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?

The core rule is front-loaded, but the four-value list is repeated three times ('not attending, attending, registered, or went' / 'skip, attending, registered, or went') and asides like the CRM-22 ticket reference and 'whether your human goes is theirs' add rhetorical bulk rather than decision-relevant information.

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 two-parameter mutation with full schema coverage and clear annotations, the description covers authorization source, timing rule, effect, and the alternative tool. The only gap is response/overwrite behavior, which is minor since no output schema exists and the effect is stated.

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% and the enum is documented, so the baseline would be 3. The description earns more by explaining the semantic weight of 'went' (only valid after the event date) and by framing the values as 'the verb that fits' found events — nuance the schema does not carry.

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 ('Record where you stand on an event') and enumerates the exact accepted states. It also carves out the boundary against crm_update_event, which handles the outcome rather than attendance, so an agent can tell the two apart without opening either schema.

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?

Explicit when-to-use and when-not: 'ONLY ON YOUR HUMAN'S WORD... If they said it, record it; if they did not, ask,' which rules out inference from any other source. It also gives a temporal rule ('went is for after the date') and names the sibling to use instead for outcomes.

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