list_calls

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

The annotation readOnlyHint=true already covers the side-effect profile. The description adds that it lists recent calls and includes durationMs/resultBytes, but it does not disclose behavioral details such as ordering, pagination, time window, or any limits. With annotations present, the bar is lower, but the description still misses easily communicated behavior.

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 a single, front-loaded sentence with no redundant words. It states the verb, resource, and included fields in an efficient structure that is immediately scannable.

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 zero-parameter tool with no output schema, the description provides the core purpose but leaves ambiguity around what 'recent' means (time window), the maximum number returned, ordering, and return format (array vs object). These gaps are not filled by the schema or annotations, so the description is minimally viable but not fully complete.

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?

There are zero parameters, so the baseline is 4. The description correctly omits parameter information, and no parameter semantics are needed since the schema is empty. No deduction is warranted.

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 uses a specific verb ('List') and resource ('recent MCP tool calls') and names the returned fields (durationMs, resultBytes). This clearly differentiates it from sibling tools like list_tasks or browser operations, so an agent can identify its exact purpose.

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?

Usage is implied: when you need to inspect recent tool call performance. However, it does not explicitly state when to use this tool versus alternatives, nor any temporal or scope conditions. The absence of similar siblings reduces the need, but the guidance remains implicit rather than explicit.

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