update_variable

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only says 'update' without mentioning side effects, whether changes propagate to bound usages, whether the operation is reversible, or whether special permissions are required.

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 economical at one sentence and has no filler. However, it is under-specified rather than information-dense: it only restates the tool's core action and does not mention the important mode parameter or any usage conditions.

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?

With no annotations, no output schema, and a short generic description, the definition leaves meaningful gaps for a mutation tool. It does not clarify what happens when mode is omitted, whether variable name updates are supported, or what success looks like.

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 already covers all parameters with 100% description coverage, including variableId, value, and mode. The description adds no parameter meaning beyond the schema, so the baseline score of 3 is appropriate.

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 a specific verb and resource: 'Update a variable value.' This clearly conveys that the tool modifies an existing variable's value rather than creating or deleting one. However, it does not differentiate among sibling tools like bind_variable, swap_mode, or create_variable, all of which are conceptually related.

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 prefer this tool over alternatives such as create_variable, bind_variable, or delete_variable. It also does not explain when the optional mode parameter should be used relative to the default update path.

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