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

Annotations already flag destructiveHint=true and idempotentHint=true; the description earns credit by explaining *why* – it overwrites the current name and any extra field named in update_mask is cleared or reset to its default. That is real behavioral context beyond the structured fields. It doesn't address permissions or failure behavior, but the output schema covers return values.

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?

Two tightly packed sentences with the destructive constraint front-loaded before the caveat. The trailing "Tools revision: d80f65c0." is boilerplate noise that adds nothing for an agent.

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 destructive three-parameter mutation with 0% schema documentation, the description supplies the essential warning about update_mask side effects and the single-field scope. With annotations and an output schema present, nothing critical is missing; only name-format and permission prerequisites are unstated.

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 0%, so the description must carry all three parameters, and it largely does: name is the resource identifier, display_name is the sole renameable field, and update_mask must stay "displayName" or side effects occur. The only gap is that it doesn't spell out the expected resource-name format.

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 opens with a specific verb+resource ("Rename a data stream") and immediately constrains scope to "display_name only", which cleanly separates it from ga4_create_data_stream and ga4_list_data_streams. An agent knows exactly what this tool mutates without opening the schema.

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?

It states the operating condition (only renaming is possible, so any other update intent is out of scope) and gives an explicit do-this instruction for update_mask. It stops short of naming alternatives (e.g. ga4_update_property) for other field changes, but the constraint is clear enough to steer selection.

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