cancel_send

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

Discloses irreversibility, authentication via API key, max 10 concurrent requests, and respect for read-only and dry-run modes. Since no annotations exist, the description fully covers behavioral traits.

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 concise and well-structured, front-loading the main action, followed by constraints, alternatives, and additional details. Every sentence adds value without redundancy.

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 tool has one parameter and an output schema, the description fully explains the return format (JSON with status and campaign_id) and error handling, making it self-contained and complete.

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?

The input schema has one parameter (campaign_id) with no description. The description adds an example ('abc123def4') and a validation constraint ('Must be in sending status'), providing essential 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 tool cancels a campaign mid-send, stopping delivery to remaining recipients. It uses a specific verb ('cancel') and resource ('campaign mid-send'), and distinguishes from siblings like 'unschedule_campaign'.

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 (campaigns in 'sending' status) and when not to (use unschedule_campaign for scheduled campaigns). Also notes that already-delivered emails cannot be recalled.

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