explain

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

The description adds the useful detail that the tool reports on the 'winning plan chosen by the query optimizer,' implying it evaluates query planning rather than just returning raw results. It also mentions 'execution,' which hints that queries may actually run to collect statistics. However, annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. No additional behavioral traits (e.g., performance implications, permission needs) are disclosed.

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, focused sentence that front-loads the action ('Returns statistics') and specifies exactly what the statistics describe. There is no fluff, repetition, or tangential information. It is appropriately compact given the tool's complexity.

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?

The tool is moderately complex (4 params, nested method schema, enum verbosity), but the extensive schema descriptions cover all parameters and their meanings. The main description provides a clear high-level purpose, and an output schema exists, so return values don't need explanation. The only gap is the lack of explicit use-case hints, but that's not a completeness issue given the schema richness and annotations.

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%, with all four parameters (database, collection, method, verbosity) having descriptions. The main description adds no parameter-specific meaning beyond the schema. For example, the schema's verbosity description explains the trade-offs between queryPlanner and executionStats, which is richer than anything in the main text. Baseline 3 is appropriate since the description doesn't need to compensate.

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 a specific action and resource: 'Returns statistics describing the execution of the winning plan chosen by the query optimizer for the evaluated method.' It distinguishes this tool from siblings like find/aggregate (which execute queries and return results) by focusing on query plan analysis. The verb 'Returns' makes the primary function explicit.

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 no guidance on when to use this tool versus alternatives, nor any exclusions or prerequisites. It does not state 'use this to analyze query performance' or contrast with sibling tools. The only usage hint is buried in the schema's verbosity parameter description (e.g., use executionStats for execution time), which is about verbosity selection, not tool selection. The agent is left to infer when to invoke explain.

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