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

Annotations already declare readOnlyHint=true, so the description's 'Read-only' adds no new information. However, the description does add behavioral context by enumerating what can be reviewed (status, payment state, publication state, guest counts, configuration), which helps the agent understand the scope of the operation. It doesn't disclose return format or error behavior, but the output schema exists to cover that.

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 description is a single, well-structured sentence that front-loads the trigger condition ('Use this when...') and then lists the specific aspects covered. It ends with 'Read-only' as a concise behavioral qualifier. No wasted words.

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 simple read-only tool with one parameter and an output schema, the description is largely complete. It clearly states the purpose and scope. The only minor gap is not explicitly stating that event_id is the identifier of the invitation to fetch, but this is easily inferred from the parameter name and the tool's name. The output schema covers return values, and annotations cover safety.

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 0%, so the description must compensate for the single parameter event_id. The description mentions 'a Lemonvite invitation' but does not explicitly explain that event_id identifies the invitation. However, with only one parameter named event_id, the meaning is fairly inferable. The description adds some context by listing what details can be reviewed, but it doesn't directly map event_id to the invitation being reviewed.

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 clearly states the tool's purpose: reviewing current details, status, payment state, publication state, guest counts, or configuration of a Lemonvite invitation. It uses a specific verb ('review') and resource ('Lemonvite invitation'), and the read-only qualifier distinguishes it from mutation siblings like update_invitation or publish_invitation.

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?

The description explicitly says 'Use this when the user wants to review...' which provides clear context for when to invoke it. It doesn't explicitly name alternatives or exclusions, but the read-only nature and the list of reviewable aspects imply when not to use it (e.g., not for modifications). Sibling names like update_invitation and publish_invitation make the boundary clear enough.

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