ga4_check_compatibility

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

The description declares the tool as 'Read-only', indicating no side effects. It also explains why the check is needed (the Data API rejects incompatible pairs). While no annotations are present, the description adequately covers behavioral aspects. A minor improvement could be mentioning speed or rate limits, but it's sufficient.

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, consisting of two sentences with no unnecessary words. It front-loads the purpose and includes essential usage guidance. Every sentence adds value.

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?

The description is complete for a simple compatibility-check tool. It explains the purpose, usage context (before ga4_run_report), expected behavior (read-only), and action on incompatible results. No output schema is needed given the simplicity.

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?

The input schema covers all three parameters with descriptions (100% coverage). The description adds context by mentioning 'given GA4 dimensions/metrics' but does not provide additional semantic meaning beyond what the schema already offers. Baseline 3 is appropriate.

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's purpose: to check which GA4 dimensions/metrics can be combined in one report. It uses a specific verb ('check') and resource ('GA4 dimensions/metrics compatibility'), and distinguishes itself from siblings like ga4_run_report by advising to call it before ga4_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 provides explicit guidance on when to use the tool ('BEFORE ga4_run_report when combining unusual dimensions/metrics') and what to do if incompatibility is found ('drop or replace anything reported incompatible instead of retrying blind'). This clarifies usage and alternatives.

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