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

Annotations already declare readOnlyHint and idempotentHint, and the description consistently uses 'Read' with no side effects mentioned. It adds useful behavioral context about field parity with fetch_leads, though it does not discuss error behavior or edge cases, which is acceptable given 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?

Two sentences pack the essential purpose, usage conditions, and parameter relationships without redundancy. The most important guidance is front-loaded, making it easy to parse.

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?

The description adequately covers the tool's role in the workflow, including how it relates to fetch_leads and get_campaign_stats. Given the output schema exists and annotations provide safety cues, an agent has enough context to call this correctly.

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?

All three parameters are described in the schema and the description adds extra value: campaignId warns to never invent one, leadIds gives a concrete example from get_campaign_stats, and limit notes a default of 50 not present in the schema. Coverage is complete and meaningful.

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 uses specific verb 'Read' and clearly identifies the resource (campaign leads) and scope (ANY campaign by campaignId). It distinguishes from fetch_leads by noting the jobId limitation, making purpose unambiguous.

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 this tool: for campaigns not started in the session, and when resolving leadIds from get_campaign_stats. It also clarifies that fetch_leads only works with a jobId from the agent's own find_leads call, providing actionable guidance.

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