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

Annotations cover only the safety profile (readOnly=false, destructive=false, openWorld=true). The description adds hard operational facts beyond them: caps of 1,000 total and 500 by email with failure over cap, that email invitees still authenticate by phone for RSVP, and that calls are confirmed by default but that can be toggled off. This is exactly the kind of disclosure annotations cannot carry.

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 core action and the two invite routes, then layers constraints. Mostly earns its sentences, though the RSVP-by-phone aside and the confirmation-toggle note add length that is useful but not strictly invocation-critical.

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 mutation tool with no output schema, the definition covers the cap behavior, the confirmation requirement, auth prerequisites (Cotlet API key with app access), and the parameter sources. Nothing an agent needs to call it correctly is missing.

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 event_id, user_ids and emails. The description reinforces provenance ('from list_past_guests', 'the addresses you give') but adds no syntax or format detail beyond the schema. Baseline 3 applies 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 (invite) plus two distinct resources/routes: past guests and mutuals via Partiful, or anyone via email. This differentiates it cleanly from siblings like partiful_send_text_blast (messaging) and partiful_approve_guests (approval workflow). An agent knows exactly what the tool 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?

Names the source list for user_ids ('people you pick from list_past_guests') and the email route, and gives a genuine usage rule ('Reaches other people: confirm with the user before each call'). It stops short of explicitly contrasting against alternatives such as send_text_blast, but context for when to invoke is clear.

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