gerbil-mcp

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It describes the action ('scanning the installation') and output format ('Returns module paths like :std/text/json, :std/iter, etc.'), which adds useful context beyond the input schema. However, it lacks details on potential side effects, error handling, or performance implications (e.g., scanning might be resource-intensive), 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 front-loaded with the core purpose in the first sentence, followed by optional filtering and return details in subsequent sentences. Each sentence earns its place by adding necessary information without redundancy, making it efficient and well-structured for quick understanding.

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 low complexity (1 optional parameter, no output schema, no annotations), the description is mostly complete. It covers the purpose, usage with filtering, and output format. However, without an output schema, it could benefit from more detail on the return structure (e.g., list format, error cases), slightly reducing completeness for agent invocation.

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 has 100% description coverage, with the single parameter 'prefix' fully documented in the schema. The description adds minimal value by reiterating the filtering purpose and providing examples ('e.g. "std/text", "std/net", "gerbil"'), but does not explain semantics beyond what the schema already states, such as how the prefix matching works (e.g., case sensitivity). Baseline 3 is appropriate as the schema does the heavy lifting.

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 specific action ('List available Gerbil standard library modules by scanning the installation') and resource ('Gerbil standard library modules'), distinguishing it from siblings like gerbil_apropos (search) or gerbil_check_syntax (validation). It explicitly mentions what it returns ('module paths like :std/text/json, :std/iter, etc.'), making the purpose unambiguous.

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 context for usage by mentioning the optional filtering capability ('Optionally filter by prefix'), which helps differentiate it from tools like gerbil_module_exports (which might list exports of a specific module). However, it does not explicitly state when not to use this tool or name specific alternatives among siblings, such as using gerbil_apropos for searching modules by content rather than listing.

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