cancel_send

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

With no annotations, the description fully discloses behavioral traits: irreversibility, status precondition, authentication via API key, max 10 concurrent requests, respect for read-only/dry-run modes, and error handling for invalid status.

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?

Highly concise: first paragraph states action and constraints, then structured Args/Returns sections. No wasted sentences; every line adds value. Well-organized for quick parsing.

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 one parameter, no annotations, and output schema existence (described), the description covers all necessary context: preconditions, side effects, auth, rate limits, error cases, and return format. Completely sufficient for correct invocation.

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?

Despite 0% schema description coverage, the description fully explains the `campaign_id` parameter: provides format example ('abc123def4'), clarifies it must be the ID of a campaign in 'sending' status, and implies requiredness. Adds significant meaning beyond the schema.

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 action: 'Cancel a campaign mid-send, stopping delivery to remaining recipients.' It also distinguishes from sibling tool `unschedule_campaign` for scheduled campaigns, providing clear purpose differentiation.

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 states when to use: 'Only works on campaigns with status 'sending'' and when not to use: 'Already-delivered emails cannot be recalled.' Provides direct alternative: 'Use unschedule_campaign for scheduled (not yet sending) campaigns instead.' Also covers authentication and rate limits.

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