Update group CI/CD variable

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

The description adds one behavioral detail: it does not return the value after update. With annotations already providing readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, this is a modest addition. It does not disclose auth needs, error behavior, or effect on existing settings, but the annotation coverage reduces the burden.

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 sentence with no fluff. It is extremely concise and front-loaded with the action and a key behavioral note. Perfectly sized for a brief tool description.

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 complexity of 10 parameters and a large sibling set, this description is severely under-specified. It does not mention that the variable must already exist, how the key identifies it, or any side effects beyond not returning the value. The output schema exists but doesn't compensate for the missing parameter context and usage semantics.

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 only 20% (only raw and group have descriptions). The tool description provides no information about the parameters, such as which ones are required (group, key, value) or the meaning of optional flags like masked, protected, variable_type, etc. The description fails to compensate for the low schema coverage.

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 tool updates a group CI/CD variable, distinguishing it from create and delete siblings. It also specifies a key behavioral aspect (does not return the value), making the purpose specific and unambiguous.

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 implies the tool is used to modify an existing group CI/CD variable but does not explicitly state when to use it versus create or delete, nor does it mention prerequisites like needing an existing variable or authorization. There is no guidance on alternatives.

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