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

Annotations already declare readOnlyHint=true, and the description confirms it is 'Read-only.' Beyond that, it adds valuable behavioral context: it mentions the tool returns personal invite links and party sizes, and that rsvp_status can be used as a filter. This enriches the agent's understanding without contradicting the annotation. The absence of pagination or limit details is a minor gap, so a 4 fits.

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 two sentences, with the primary purpose and included data front-loaded in the first sentence, and the filter usage and read-only note in the second. There is no filler or redundancy; every clause adds useful 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?

Given the simplicity (2 params, one optional enum) and that an output schema exists, the description need not explain return values. It covers the purpose, the filtering behavior, and the read-only nature. It does not mention pagination or error handling, but those are not explicitly required for this straightforward read tool. It is complete enough for an agent to call it correctly, so a 4 is justified.

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 explain the parameters. It clarifies that event_id refers to a Lemonvite invitation (implicitly the target) and that rsvp_status is a filter, with a concrete example 'who has not responded'. It does not list the enum values, but those are in the schema. For a two-parameter tool, this covers both meanings adequately, earning a 4.

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 states a specific verb (list/see) and resource (guest list of a Lemonvite invitation), and enumerates the included data: per-guest RSVP status, party sizes, and personal invite links. It is clearly distinct from siblings like get_invitation or get_rsvp_summary, which focus on the invitation itself or aggregated counts, and it even gives a concrete filtering use case ('who has not responded').

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 see the guest list' and provides a filtering example, giving clear context for when to invoke it. However, it does not name any alternative tools or explicitly state when not to use it (e.g., if a summary is needed, use get_rsvp_summary). This is clear context but lacks exclusions, so a 4 is appropriate.

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