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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds meaningful behavioral context beyond that: the tool renders an interactive MCP app, provides a visual view, and returns a short text summary. No contradiction with annotations.

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 main purpose and metric list, followed by usage preference and output format. 'When the user asks about this' is slightly vague filler, but overall the text is compact and each sentence contributes useful information.

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?

With one optional parameter, full schema coverage, a rich output schema, and annotations covering safety and idempotency, the description fully enables correct invocation and selection. It covers choice rationale, rendering behavior, and output format; nothing material is missing.

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 for the single 'range' parameter, including its enum values and default of 30d. The description adds no parameter-specific detail, but the schema already carries the full semantic load, so baseline 3 is appropriate.

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?

Description states a specific verb and resource: 'Show a rich overview of wearable health signals' and enumerates the included signals (steps, Zone Minutes, resting heart rate, HRV, VO2max, stress). It distinguishes from sibling metrics tools by framing this as a broad overview for overall health-trend questions.

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?

Description explicitly says to prefer this tool for 'broad wearable or overall health-trend questions' and to render the interactive MCP app rather than describing rows in text. It does not name specific sibling alternatives or exclusion conditions, but the guidance is clear enough for an agent to choose correctly.

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