update_custom_field

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

The description labels the operation 'Mutating' but provides no details on side effects, success conditions, error handling, idempotency, or rate limits. With no annotations available, the description carries the full burden, which it fails to meet.

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 a single, front-loaded sentence with no wasted words. It is concise, but the brevity sacrifices valuable information that could be added without significant bloat.

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 simple two-parameter update tool with no output schema, the description is minimally adequate in stating the action, but it lacks context on what a custom field is, the effect of the update, and behavioral details. An agent has enough to understand what the tool does but not enough to use it optimally.

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 the schema already defines both parameters (name and field_id). The description adds no extra meaning beyond 'update', so a baseline score of 3 is appropriate.

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 explicitly states 'update a SendGrid marketing contact custom field definition', using a specific verb ('update') and resource ('custom field definition'), clearly distinguishing it from sibling tools like create_custom_field and delete_custom_field.

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?

No guidance is provided on when to use this tool versus alternatives, such as when to update versus create or delete a custom field, nor any prerequisites or context that would help an agent decide.

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