set_contact_custom_fields

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

No annotations are provided, so the description must carry the full burden. It mentions not touching standard fields, but omits critical behaviors: whether it replaces all custom fields or merges, required permissions, idempotency, and error handling.

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?

A single, direct sentence with no unnecessary words. Perfectly concise for the information it conveys.

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?

Despite having an output schema, the description lacks key details: parameter explanation (slug), behavior on missing fields, error conditions, and idempotency. For a mutation tool with low schema coverage, this is insufficient.

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 description coverage is 0%, meaning the description adds no explanation for parameters. The schema itself provides a detailed description for 'fields', but 'slug' remains undocumented. The description fails to clarify parameter purpose 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 description clearly states the action (set), resource (contact), and scope (custom-field values without touching standard fields). It effectively distinguishes from siblings like update_contact or other set_*_custom_fields tools.

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 when to use (for custom fields only) but lacks explicit guidance on when not to use or alternatives. With siblings like update_contact, the context is present but not leveraged for clear direction.

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