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

Annotations already flag destructive/openWorld/non-idempotent, and the description adds substantial beyond-schema context: per-event limits (1,000 total, 500 email), canceled-event refusal, host-only auth, default confirmation with opt-out, owner-approval wait, and that invited_total reflects the post-call count.

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?

Dense but front-loaded: mechanism first, then limits and constraints. A few clauses (owner-approval, confirmation) stack at the end, but nearly every sentence carries operational value.

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?

No output schema, yet it explains the return (invited_total) and covers limits, auth, and refusal cases. An agent has enough to call correctly; only minor gaps like per-call failure semantics remain.

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 the schema already documents each parameter and its constraints (maxItems, maxLength, formats). The description reinforces email-vs-user_ids behavior and what message means, but adds only marginal syntax detail beyond structured fields; baseline 3 applies.

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) and its resources (past guests, mutuals, email recipients), and clearly distinguishes itself from siblings like send_text_blast by naming the mechanisms and the list_past_guests source. An agent can identify its function 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?

Gives clear context: use for inviting via Partiful or email, sourced from list_past_guests (user_ids) or emails, and states no phone-number path exists. It lacks an explicit comparison to texting siblings like send_text_blast, but the when/mechanism guidance is solid.

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