list_tools

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

With no annotations, the description itself must convey the tool's behavior. The verb 'list' strongly implies a read-only, non-destructive operation, which is helpful. However, the description doesn't clarify the optional category filter or how results are affected by it, leaving some behavioral ambiguity about whether 'all tools' is always returned.

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 two short sentences with no wasted words. The primary function appears first, and the usage guidance is immediate and actionable. It earns its place entirely.

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 listing tool with one optional parameter and no output schema, the description is adequate for an agent to understand purpose and timing. It could mention that results can be filtered by category, but the schema already captures that, so nothing critical is missing for a low-complexity tool.

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 schema already fully documents the single optional category parameter with an enum and description, so schema coverage is 100%. The description adds no additional parameter-level meaning beyond encouraging tool discovery, which is acceptable but not additive.

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 states a clear action and resource: 'List all available MCP tools with descriptions.' This makes the tool's core purpose obvious. However, it does not differentiate itself from the sibling help_tool, so an agent might not know which discovery tool to prefer.

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 gives concrete usage context: 'Use this to discover available tools before starting a task.' This tells the agent when to invoke it. It does not explicitly mention alternatives or when not to use it, so it falls just short of the highest bar.

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