ga4_create_data_stream

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

Annotations already declare readOnlyHint=false and idempotentHint=false, so the agent knows this is a mutating, non-idempotent write. The description adds genuinely new context beyond that: the server cannot delete the stream afterwards, so creation is effectively irreversible. This is valuable since destructiveHint=false might otherwise imply easy reversibility.

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?

Front-loaded with the action and return value, then usage condition, caveat, and alternatives in a logical order. Three sentences, each earning its place, though slightly dense.

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 create tool with annotations covering the safety profile, the description names the return value (measurement id), the irreversibility caveat, and prerequisite/alternative tools. No output schema exists, but the description states what is returned, so the agent has enough to call it correctly.

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 description coverage is 100%, so the schema already documents url, property_id, and stream_name with examples. The description adds no syntax or format detail beyond what the schema provides. Baseline 3 is appropriate when the schema does the heavy lifting.

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?

States a specific verb+resource ('Create a web data stream on a Google Analytics 4 property') and even names the return value ('return its measurement id'). This clearly distinguishes it from siblings like ga4_list_data_streams and ga4_create_property.

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?

Explicitly states when to use it ('when the user needs a measurement id to install analytics on a site') and routes to alternatives with conditions: call ga4_list_data_streams if a stream may already exist, and ga4_create_property first when the property does not exist. Nothing is left to inference.

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