Set Project Variable

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

Annotations provide idempotentHint=true. The description adds that the variable is accessible as @key, but fails to disclose other behavioral traits such as overwrite behavior, persistence, or scope. Minimal added value beyond annotations.

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 extremely concise with two sentences, front-loaded with the verb, and contains no redundant words. Every sentence is purposeful.

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 simple tool with 2 parameters and no output schema, the description explains the purpose and usage. However, it lacks completeness by not specifying overwrite behavior, data type constraints on value, or that variables persist in the project file.

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 0%, placing full burden on the description. However, the description does not explain parameter semantics (e.g., valid key format, value constraints, or reserved keys). It merely mentions key and value implicitly, providing no added meaning.

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 verb 'Set' and resource 'project-level variable', and adds context about accessibility in expressions as @key. However, it does not explicitly distinguish from sibling tools like 'set_setting', which might be confused.

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 usage for setting variables used in expressions but provides no guidance on when not to use it or alternatives. No exclusions or context for selection among siblings.

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