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

With readOnlyHint:true already covering the read-only nature, the description adds substantial behavioral context: missing windows are genuine gaps (never interpolated), percentile withholding conditions with exact sample thresholds, and the flagged definition including the explicit note that absolute thresholds are unsupported. These details are not present in annotations or schema and are critical for interpreting results correctly.

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, dense sentence that front-loads the core purpose and then packs in critical data-handling rules. It is efficient with no filler, though the density of clauses makes it slightly harder to parse at a glance. Every piece of information earns its place, so it is highly concise, but the structural density slightly reduces readability.

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 there is no output schema, the description thoroughly explains what the tool returns: the distributions, time series, handling of missing windows, percentile reliability conditions, and the flagged definition. An agent has enough information to understand the result and its caveats without needing additional documentation. The 5-parameter tool with 2 required is well-served by this description.

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 has 100% parameter description coverage, so all five parameters are already documented. The description adds no parameter-specific semantics beyond what the schema provides (e.g., from/to as window boundaries are already described). It does reference the 60s window granularity, which subtly reinforces the meaning of from/to, but this is not a significant addition.

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 specific resource ('Single-rule latency detail') and the exact data it returns (merged phase × cacheState distributions plus a per-window time series). This clearly distinguishes it from siblings like lexq_profile_overview, which is the group-level counterpart. The verb is implicit but the resource and scope are unmistakable.

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 implies usage through its name and specificity (single-rule detail vs. overview), but it does not explicitly state when to choose this over lexq_profile_overview or any other alternative. No exclusions or alternative routing are mentioned, leaving the agent to infer the intended use case from naming conventions.

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