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

Goes beyond the annotations (readOnlyHint=false, destructiveHint=false, openWorldHint=true) by explaining that guests are not contacted until send_invitation, that removal happens in the app, and that no confirmation dialog is required. It also states an auth prerequisite (Cotlet API key with app access). Good added context over the structured hints.

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-loaded with the core action, but it repeats the same point twice ('Nothing is sent until send_invitation' and 'Nothing reaches the guests until send_invitation') and re-states the title. The run-on about removal and confirmation is loosely worded, so several sentences don't fully earn their place.

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 no output schema and annotations already covering the safety profile, the description supplies the key missing context: send timing, no-confirmation behavior, and auth needs. It is largely complete, with only minor redundancy rather than real gaps.

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%, so both parameters are already documented (guests format string and event_id sourced from list_events). The description adds only that each guest needs a name plus email or phone, which largely restates the schema's item format. Baseline 3 is appropriate when the schema does the heavy lifting.

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 (add) and resource (guests) plus scope (the unsent guest list of an event), which cleanly separates it from siblings like paperless-post_send_invitation and paperless-post_list_guests. An agent can tell what this does without opening the 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?

Explicitly routes to the alternative by twice noting 'Nothing is sent until send_invitation,' so the agent knows this is the pre-send staging step. It also clarifies that it fills the same list as the spreadsheet upload. It stops short of naming exclusions or the reverse case (when not to add guests).

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