javalens-mcp

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

With no annotations provided, the description carries the full burden and does well by explaining the tool's analysis process ('determine which variables become parameters', 'determine return type'), output format ('text edits for method declaration and call site'), and important behavioral detail ('uses ZERO-BASED coordinates'). It doesn't mention error conditions or performance characteristics, keeping it from a perfect score.

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 well-structured with clear sections (purpose, usage, output, analysis details, important note, prerequisite). Every sentence adds value, with no redundant information. The information is front-loaded with the core purpose stated first.

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 complex code transformation tool with no annotations and no output schema, the description does an excellent job explaining what the tool does, how to use it, and what to expect. It covers the transformation logic, coordinate system, and prerequisite. The only minor gap is not explicitly describing the format of 'text edits' in the output.

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?

With 100% schema description coverage, the baseline is 3. The description adds some context about 'zero-based coordinates' which clarifies the coordinate parameters, and mentions 'method name' as a required input, but doesn't provide additional semantic details beyond what the schema already documents for each parameter.

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's purpose with specific verbs ('extract a code block into a new method') and distinguishes it from siblings like 'extract_constant' or 'extract_variable' by focusing on method extraction. It goes beyond the tool name to explain the transformation process.

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 explicit usage instructions ('Select code range, provide method name'), includes a prerequisite ('Requires load_project to be called first'), and distinguishes when to use this tool versus alternatives by specifying it's for method extraction (unlike extract_constant or extract_variable).

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