Update GTM Tag

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

Annotations already flag readOnlyHint=false, destructiveHint=true, and idempotentHint=true. The description adds valuable behavior beyond the annotations by explaining that only provided fields are changed and that provided array fields replace existing arrays wholesale, which is important update semantics for the agent to know.

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 a single, front-loaded sentence that states the core action first and then the key behavioral caveat. Every word earns its place; there is no redundancy or filler.

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?

Given the 9-parameter schema, full schema coverage, and the presence of safety annotations, the description covers the most critical behavioral nuance. It does not explain return values, but no output schema is defined and the schema/annotations already handle most operational context.

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 100%, so the baseline is 3. The description adds extra meaning by clarifying the partial-update contract: omitted fields remain unchanged and array fields are replaced rather than merged. This is a meaningful addition beyond the individual parameter descriptions in the schema.

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 states 'Update an existing tag in a workspace' with a specific verb and resource, clearly distinguishing this mutation tool from sibling create/delete/get/list tag tools. The phrase 'existing tag' also clarifies that this is not for creation.

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 clearly implies this tool is for modifying an already existing tag, providing context for when it should be used. It does not explicitly name alternatives or exclusion cases, but the sibling tool names and 'existing tag' wording give adequate contextual guidance.

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