ga4_update_custom_metric

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

Discloses write operation, immutability constraints, and configuration requirements. No annotations provided, so description carries burden but omits side effects, auth beyond flags, 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?

Single, well-structured sentence with clear prefix [GA4 WRITE]. Every part adds necessary information; no 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?

Covers key update behavior and prerequisites, but lacks return value description (no output schema) and error handling details. Adequate for experienced users but could be more complete.

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 50% (3 of 6 params described). Description adds value by explaining updateMask derivation and immutable fields, but does not elaborate on undocumented params (description, displayName, measurementUnit).

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?

Clearly states it updates a custom metric, distinguishes from create (sibling ga4_create_custom_metric) and archive. Specifies immutable fields, making purpose precise.

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 prerequisites (GA4_MCP_ENABLE_WRITES=true, confirm=true) and updateMask derivation guidance. Lacks explicit when-not-to-use but context implies update vs. create/archive alternatives.

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