zernio_update_contact_field

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

No annotations are provided, so the description must convey behavior. It indicates a mutation ('Update') but does not disclose whether values are overwritten or appended, any side effects, or required permissions. The agent lacks insight into the tool's operational behavior.

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 that efficiently conveys the tool's purpose. Every word is meaningful, and there is no extraneous information.

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?

The tool is simple with 3 required params and no output schema. The description is minimal but provides the core purpose. However, it lacks details about return value and the semantics of the update (e.g., whether the field must already exist). For a mutation tool, more context would be beneficial.

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?

The input schema has 100% coverage with descriptions for contactId, fieldSlug, and value. The description adds no further semantics beyond the schema, so baseline 3 is appropriate. It does not explain format, constraints, or relationships between parameters.

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 'Update a custom field value for a contact' clearly states the action (update) and the resource (custom field value for a contact). It distinguishes this tool from sibling tools like create_contact, add_contact_tag, and update_contact by specifying the custom field focus.

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. It does not mention prerequisites (e.g., that the contact and field must exist) or when not to use it. The description lacks context for selective tool invocation.

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