Check dimension/metric compatibility

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false. The description adds that the tool queries GA4 for compatibility and returns compatible additional fields, which is useful but does not go into details like return shape, pagination, or error 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 two sentences with no filler. The core action is front-loaded, and the usage guidance is placed immediately after the functional explanation.

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 simple read-only compatibility check, the description provides the essential context: what it checks, what it returns conceptually, and when to use it. There is no output schema, so a little more detail about the response format or the effect of onlyIncompatible would be helpful, but the description is still sufficient for basic invocation.

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 only 50%; metrics and dimensions lack schema descriptions. The description does explain that these parameters represent 'a set of dimensions and metrics' checked for compatibility, but it does not fully compensate by clarifying formats, allowed values, or edge cases like empty arrays.

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 uses a specific verb and resource: 'Ask GA4 whether a set of dimensions and metrics can be queried together' and 'which additional fields are still compatible.' It clearly differentiates itself from the sibling ga_run_report by saying 'Use before building an unusual ga_run_report.'

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 gives a clear usage context: use before building an unusual ga_run_report. It does not explicitly list alternatives or when-not-to-use scenarios, but the context is specific enough for an agent to select this tool appropriately.

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