update_merge_field

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

With no annotations, the description carries full burden. It covers partial update behavior (only provided fields changed), choices replacement (old lost), immutability of type/tag, authentication, rate limit, and error response (404). However, it does not detail behavior under read-only/dry-run modes or other potential errors beyond 404.

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 concise and well-structured. It opens with the core purpose, then explains important behaviors in separate paragraphs, and lists parameters with clear formatting. Every sentence adds information without redundancy.

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 tool has 6 parameters (2 required) and no annotations, the description covers all essential aspects: purpose, usage guidelines, parameter semantics, error conditions, and return values (output schema described). It references sibling tools for type/tag changes, making it complete for an agent to use correctly.

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?

Despite 0% schema coverage, the 'Args' section in the description provides detailed meaning for each parameter: format hints (list_id: 10-char alphanumeric, merge_id: numeric string), behavior (choices replaced entirely, ignored for non-dropdown/radio types), and defaults (only provided fields updated). This adds substantial value beyond the schema's bare type information.

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 ('Update a merge field's name, default value, required flag, or dropdown/radio choices') and specifies the resource (merge field). It distinguishes itself from siblings by explicitly noting not to use for changing type or tag, referring to delete_merge_field and create_merge_field as alternatives.

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 provides explicit guidance on when to use this tool (updating specific fields) and when not to (changing type or tag, where delete+create is recommended). It also mentions usage constraints: authentication via API key, max 10 concurrent requests, and respect for read-only/dry-run modes.

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