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

Annotations already signal mutation (readOnlyHint: false), but the description adds valuable behavioral context: up to 50,000 records across 500 pages, creates-or-merges semantics, deduplication by email/LinkedIn URL, optional ICP filtering, and asynchronous execution for large lists. This goes well beyond the 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?

The description is compact and well-structured: main action first, then key behaviors, then async caveat, then cross-references to sibling tools. Every sentence contributes meaningful information with no filler.

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 6-parameter import tool with no output schema, the description covers the data source, scale limits, deduplication, ICP filtering, async behavior, and how to find valid inputs and track progress. An agent has enough context to invoke the tool correctly and interpret follow-up steps.

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 high (83%), and the description adds extra meaning by telling the agent to use campaignstack_list_apollo_sources for valid listId values, which is not explained in the schema. It also clarifies the onlyMatchingIcp option and its relationship to campaignId. Modest but useful added semantic value.

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 uses a specific verb ('Import') with a clear resource ('Apollo contact list into CampaignStack'), and details what the tool does: fetches contacts, creates/merges leads, and deduplicates by email and LinkedIn URL. It is unmistakably distinct from sibling import tools like campaignstack_import_external_leads or campaignstack_import_leads_csv.

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 clearly states when to use this tool (importing from an Apollo list), mentions optional ICP filtering, and explicitly points to sibling tools for finding valid listId values (campaignstack_list_apollo_sources) and checking async status (campaignstack_get_apollo_import_progress). It does not explicitly contrast with other import tools, but the context is clear enough.

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