campaign_results

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

Adds significant detail beyond readOnlyHint annotation: clarifies bounce is HARD only, opens not tracked, and 404 response. No contradiction with annotations.

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?

Three efficient sentences covering purpose, input/output format, and explicit usage guidance. No unnecessary words.

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?

Fully describes a simple read operation: input, output fields, error case, and relationship to sibling tools. No output schema needed.

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% with description for campaignId. Description restates that input comes from launch_campaign but adds no new meaning beyond 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?

Description states 'Outcome counts for ONE campaign' - specific verb and resource. Clearly distinguishes from sibling tools by naming 'metrics' and 'list_campaigns' as alternatives.

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 says when to use this tool (single campaign results) and alternatives (metrics for account-wide, list_campaigns for all). Also specifies input source and 404 handling.

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