Update project CI/CD variable

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

Annotations already indicate write behavior (readOnlyHint=false), not idempotent, not destructive. The description adds the useful behavioral note that it does not return the value, which helps the agent set expectations. However, it does not clarify whether the variable is created if missing or if only existing variables are updated, which would be valuable. Given annotations carry some weight, a score of 3 is appropriate.

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 concise sentence, free of filler and front-loaded with the core action. It is appropriately sized for the tool's purpose, though it omits critical details that could be conveyed in a few more words. The structure is clean, but the brevity contributes to incompleteness.

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 tool has 10 parameters and only 20% schema description coverage, the description is far too thin. It provides no context about parameter interplay, typical use cases, or behavior beyond the basic update. The presence of an output schema does not compensate for the lack of parameter and usage guidance. A minimal but more informative description (e.g., mentioning key parameters like 'key' and 'value' and the effect of 'raw') would raise completeness.

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 has 10 parameters with only 20% description coverage (only 'raw' and 'project' have descriptions). The description adds no parameter information whatsoever. It does not explain what 'key', 'value', 'masked', 'protected', 'variable_type', 'environment_scope', etc. mean or how they affect the update. Since schema coverage is low, the description fails to compensate, leaving the agent with limited understanding of the required and optional parameters.

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 action (update), the resource (project CI/CD variable), and adds a useful qualifier (without returning its value), which distinguishes it from get_project_ci_variable (which returns the value) and create_project_ci_variable (which creates a new variable). This is a specific and unambiguous purpose.

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 gives no guidance on when to use this tool versus alternatives like create_project_ci_variable or delete_project_ci_variable. It does not mention prerequisites (e.g., variable must already exist) or when an update is appropriate. Sibling tools are listed but not referenced, so the agent gets no usage context.

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