import_contacts

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

With no annotations, the description carries the full burden. It explains upsert behavior, update-only semantics, and the special rule about resubscribing opted-out contacts. It also mentions the return object structure. This covers key behavioral traits, though some edge cases are not addressed.

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 two sentences with no superfluous words. It conveys all necessary information in a compact, front-loaded manner.

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?

Given the complexity of a batch upsert tool with behavioral nuances and no output schema, the description covers the main aspects: batching, update behavior, subscription rules, and return values. Missing details like error handling or rate limits are not critical for basic use.

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%, baseline 3. The description adds value by explaining the 'sender' parameter's conditionality ('Required only for account-wide API keys; overrides default sender'), which goes beyond the schema description. The 'contacts' parameter is described as 'Rows to upsert (≤1000)' which matches 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 description clearly states the tool performs bulk import/upsert of contacts by email, distinguishing it from siblings like create_contact and update_contact which handle individual records. The verb 'import' and resource 'contacts' are specific, and the mention of batching adds clarity.

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 implies usage for bulk operations with a 1000-row limit and batching advice, but does not explicitly state when to use alternatives (e.g., create_contact for single inserts) or when not to use this tool.

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