ga4_update_calculated_metric

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

With no annotations, the description must fully disclose behavior. It explains the write nature and partial update behavior (via updateMask derivation) and required env var/confirmation. But it lacks details on side effects, error handling, idempotency, or response format.

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 two sentences, front-loaded with purpose, then usage details. Every sentence adds value with no redundancy. Highly efficient.

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 purpose, usage pattern, and requirements, but lacks return value description (no output schema) and handling of body vs flat fields interaction. Adequate for a moderately complex tool but not exhaustive.

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 57%; the description adds meaning by listing changable fields (formula/displayName/unit), explaining update mask logic, and noting that 'body' is for advanced fields. This compensates for undocumented schema parameters, though it doesn't detail format or allowed values.

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 it updates a calculated metric, listing specific fields (formula/displayName/unit) and indicating it's a write operation with '[GA4 WRITE]'. It distinguishes from create/delete siblings by using 'update' and listing modifiable attributes, but does not explicitly contrast with siblings.

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 clear guidance: 'Pass only the fields to change; updateMask is derived from them' and mentions prerequisites ('GA4_MCP_ENABLE_WRITES=true and confirm=true'). However, it does not explicitly state when not to use this tool or suggest alternative tools.

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