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

Annotations already mark readOnly/idempotent/non-destructive, and the description adds substantial behavior beyond that: newest-first ordering, default limit and returned/total omission signal, field list, and the caveat that a campaign row exists as soon as a search starts and is often empty with leadsTotal 0. No contradiction.

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 main action is front-loaded in the first sentence, and each subsequent sentence adds useful operational detail (limit behavior, fields, follow-up routing, cohort identification, empty newest rows) without fluff. Length is justified for a central list tool.

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?

For a one-parameter list tool with an output schema and strong annotations, the description covers scope, ordering, limit semantics, return fields, caveats, and downstream tool usage. Nothing an agent needs to select or invoke it correctly is missing.

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% and the schema already explains limit and its default. The description adds the returned/total consequence of limiting, but this is primarily output behavior, so it only marginally enriches the parameter semantics 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 first sentence states a specific verb ('Lists'), resource ('campaigns (past lead searches)'), and scope ('in this workspace that the user takes part in'), plus ordering ('newest first'). It clearly separates this from sibling detail tools by naming what an id can be used for next.

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?

The description explicitly maps follow-up tools to their purposes ('get_campaign for its ICP, get_campaign_leads for its people...') and warns that generic MCP titles make title unreliable, telling the agent how to interpret results. This is more than clear context; it routes to alternatives by need.

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