update_merge_field

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

Without annotations, the description fully discloses behavior: partial update, entire replacement of choices when updating, immutability of type/tag, authentication needs, concurrency limit, dry-run mode, and 404 error handling. No contradictions.

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?

Description is well-organized: a brief summary sentence followed by a bullet-point Args section and a Returns section. Every sentence is informative and necessary, with no redundancy. Front-loaded with the core purpose.

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 6-param update tool with no annotations but an output schema, the description covers all essential: update semantics, parameter details, constraints (immutable fields), error handling, and return format. No gaps apparent.

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 description coverage, the description provides detailed explanations for all 6 parameters, including format hints (e.g., 10-char alphanumeric for list_id), how to obtain them, and specific usage notes (e.g., choices comma-separated, ignored for non-dropdown/radio). Adds significant value beyond schema types.

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 updates a merge field's specific properties (name, default value, required flag, choices) and explicitly distinguishes it from changing type/tag, which requires delete then create. This differentiates it from siblings like create_merge_field and delete_merge_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?

Provides explicit guidance: only provided fields are updated, choices are replaced entirely, and not to use for changing type/tag (instead use delete then create). Also advises where to obtain parameters (e.g., list_id from list_audiences). Clearly states authentication, concurrency limits, and dry-run mode.

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