Create Contact Import

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

With no annotations, the description carries the behavioral burden. It discloses async processing, immediate ID return, polling via a sibling tool, a 100MB size limit, and mutual exclusivity of CSV sources. This meaningfully informs the agent beyond what the schema provides, though it omits error/rate-limit details.

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, front-loaded with the primary action, then key constraints and async behavior. Every sentence contributes actionable information with zero fluff.

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?

Covers the import lifecycle by naming the polling tool and explaining the immediate return value. The complex nested columnMap schema is fully documented in the input schema, so the description doesn't need to repeat it. Lacking error handling details, but for an initiation tool with no output schema, this is adequate.

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%, so baseline is 3. The description adds value by explicitly stating 'exactly one of filePath, content, or url' and the max file size – constraints not obvious from individual property descriptions. It also references the polling parameter implicitly (the returned import ID), reinforcing the schema's purpose.

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 opens with 'Bulk-import contacts from a CSV file into Resend' – a specific verb, resource, and method. It clearly distinguishes from single-contact creation (create-contact) and positions itself as the bulk import initiation tool.

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?

Provides clear usage context: the async workflow ('returns an import ID... then use get-contact-import to poll') and a hard constraint on CSV source ('exactly one of filePath, content, or url'). It stops short of explicitly saying when not to use it relative to single-contact tools, but the context is unambiguous.

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