Glucose history and time in range

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

The annotation readOnlyHint already signals a safe read, but the description goes further by disclosing the upstream 12-hour limit, the `truncated` flag behavior, and the instruction to report the actually covered range. It also details how collection gaps are handled, which is critical for interpreting percentages. 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 around 120 words but every sentence adds necessary context: purpose, truncation behavior, gap handling, and medical disclaimer. It's front-loaded with the core function and then layers caveats efficiently.

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?

Despite lacking an output schema, the description covers the critical behavioral details: truncation, range reporting, gap handling, and the non-medical nature. It gives enough for the agent to interpret responses correctly, though it doesn't enumerate all return fields.

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%, so the baseline is 3. The description adds value by explaining that hours over 12 are ignored and that the response always reports the actual covered range, which affects how the `hours` parameter result should be interpreted. It doesn't add much about `unit`, but the schema already explains display-only conversion.

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 opens with 'Glucose readings over the last N hours (max 12)', clearly specifying the resource (glucose history) and temporal scope. It distinguishes from the sibling 'get_current_glucose' by focusing on historical data and adds the unique capability of time-in-range computation.

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 implies when to use (when historical readings are needed) without naming the sibling alternative, but explicitly states when not to use it: not for treatment decisions, not as an HbA1c/GMI estimate, and notes the 12-hour limit. This provides clear exclusions, though no named alternatives.

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