extract_variable

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

With no annotations provided, the description carries full behavioral burden. It clearly states that the tool returns text edits (not applied), uses zero-based coordinates, and requires a prior load_project call. It does not disclose error handling or edge cases, but the core behavior is transparent.

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 no wasted words. It front-loads the main purpose, followed by structured USAGE and OUTPUT sections, and concludes with an important note about zero-based coordinates. Every sentence adds value.

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 lack of output schema, the description adequately summarizes the output as 'Variable declaration and replacement edits'. It covers the essential prerequisite and coordinate system. Missing details about error conditions, but overall sufficient for a refactoring tool in a family.

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 coverage is 100% with clear descriptions for each parameter. The description adds minimal value beyond the schema, only reinforcing the coordinate system and usage pattern. It does not provide new semantic details about 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 verb 'extract' and the resource 'expression at given position into a local variable'. It effectively distinguishes from sibling tools like extract_constant and extract_method, which target different refactoring outcomes.

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 provides clear usage instructions: 'Select expression by providing start and end positions' and notes the prerequisite 'Requires load_project to be called first.' However, it does not explicitly state when to use this tool over alternatives or mention exclusion criteria.

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