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

Annotations already declare the safety profile (readOnly, idempotent, non-destructive, closed-world). The description adds genuinely new behavioral context beyond them: the tool renders an interactive MCP app, exposes a metric picker plus a range toggle, and 'Returns a short text summary alongside the visual view.' It does not cover pagination or data-freshness details, which is minor here.

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?

Two sentences, front-loaded with the capability and followed by the usage preference; the long metric enumeration is dense but each item is meaningful. No filler beyond the somewhat lengthy metric list.

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 an output schema present, the description need not explain return values, and it still gives a one-line note about the text-plus-visual return. For a single-parameter, read-only visualization tool, everything an agent needs to select and invoke it is present.

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 coverage is 100% and the single 'range' parameter is fully documented with its enum and default in the schema. The description repeats the 7d/30d/90d/1y options but omits the 90d default and adds no syntax or behavioral nuance, so it does not surpass the schema.

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 pairs a specific verb ('Show') with a well-defined resource ('body composition over time') and enumerates the covered metrics and range toggle, so the agent knows exactly what data it surfaces. It does not explicitly contrast itself with close siblings like show_body_weight or list_body_metrics, leaving differentiation implicit rather than stated.

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?

It gives a clear directive: 'When the user asks about this, prefer calling this tool and rendering the interactive MCP app over describing the underlying rows in text.' That establishes the triggering context and a rendering preference, but it names no alternative tools or exclusions, so it stops short of full when/when-not guidance.

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