javalens-mcp

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

No annotations are provided, so the description carries the full burden. It discloses that this is a search operation with a 'maxResults' parameter (implied from schema), mentions it's 'fine-grained' and unique to JDT, and states a prerequisite ('Requires load_project'). However, it lacks details on performance, error handling, or output format, leaving some behavioral aspects unclear.

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, uniqueness, usage, output, use cases, prerequisite). It's front-loaded with the core purpose and uses bullet points efficiently. However, some phrasing could be tighter (e.g., 'JDT-UNIQUE' note is slightly verbose), and it includes a minor redundancy in parameter guidance.

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 tool's complexity (search operation with prerequisites), no annotations, and no output schema, the description does a good job covering purpose, usage, and context. It explains the tool's uniqueness, provides use cases, and states a critical prerequisite. However, it lacks details on output format or error conditions, which would enhance completeness for a tool with no structured output schema.

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 100%, so the schema already documents both parameters ('typeName' and 'maxResults'). The description adds minimal value beyond the schema, only reiterating 'Provide fully qualified type name' for 'typeName' and implying result limiting via 'OUTPUT: All locations' (though 'maxResults' is not explicitly mentioned). This meets the baseline for high 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's purpose: 'Find all instantiations of a type (new Foo() calls).' It specifies the exact action (find instantiations), resource (type), and mechanism (new calls). It also distinguishes from siblings by noting 'JDT-UNIQUE: This fine-grained search is not available in LSP,' highlighting its uniqueness among analysis tools.

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 guidance: 'USAGE: Provide fully qualified type name' and 'Requires load_project to be called first.' It also lists specific use cases ('Useful for: Understanding object creation patterns, Identifying factory method candidates, Finding coupling points'), giving clear context for when to use this tool versus general search or reference-finding siblings.

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