GTM variable

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds real behavioral value by disclosing that the returned fingerprint is the prerequisite for updating the variable, which tells an agent why to call it and what to do with the result.

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?

A single tight sentence that front-loads the resource and scope, followed by the fingerprint rationale and a read-only qualifier. No filler, though the trailing 'Read only' is slightly redundant against the annotations.

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 3-parameter read tool with no output schema, the description adequately conveys what comes back (full variable with type, parameters, fingerprint) and the schema fully documents the inputs. Nothing essential to correct invocation is missing.

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%, with client_id, variable_id, and workspace_id all documented in the schema itself (including the 'never the Default Workspace' caveat). The description adds no parameter-level detail beyond what the schema already provides, so baseline 3 applies.

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: fetches one GTM variable of a workspace in full, and names the content (type, parameters, fingerprint). The word 'variable' implicitly separates it from the sibling getters gtm_get_tag and gtm_get_trigger, though neither is named explicitly.

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 parenthetical 'needed to update it' implies the intended workflow (read the fingerprint before an update), and 'Read only' clarifies the operation class, but there is no explicit statement of when to choose this over gtm_inventory or gtm_workspace_status.

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