Fetch historical CGM readings between specified start and end ISO timestamps. View continuous glucose data in mg/dL or mmol/L units from your Dexcom share.
CGM readings (every ~5 min, oldest first) between start and end.
start/end: ISO 8601 timestamps; default is the last 3 hours. Dexcom Share only serves the last 24 hours, so the window is clipped to that. units: "mg/dL" or "mmol/L".
| Name | Required | Description | Default |
|---|---|---|---|
| end | No | ||
| start | No | ||
| units | No |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does well: it discloses sampling cadence, sort order, default window, and—importantly—that the upstream source silently clips windows beyond 24 hours, a behavior an agent could otherwise get wrong. It stops short of stating auth/permission requirements or what an empty window returns.
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?
Three compact statements, front-loaded with what is returned, followed by per-parameter notes. No filler; every clause conveys a constraint or default the agent needs.
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?
For a parameterless-required read tool with no output schema, the key risks are covered: time window semantics, clipping, cadence, and ordering. It lacks only return-value detail (per-reading fields) and empty-result behavior, which are secondary given no output schema exists to imply shape.
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 0%, so the description must document all three params, and it does: start/end are ISO 8601 with a documented default, units accepts mg/dL or mmol/L. Minor gap: it doesn't say which unit is used when units is null/omitted, leaving the default unresolved.
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?
States a specific resource and scope: CGM readings in a time window, returned oldest first at ~5-minute cadence. The name plus 'CGM readings' makes the difference from get_current_glucose and get_glucose_stats inferable, but the description never explicitly contrasts itself with those siblings.
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?
Gives useful defaults (last 3 hours) and a hard availability ceiling (Dexcom Share only retains 24 hours, so requests are clipped), which is real usage guidance. However, it never says when to prefer this over get_current_glucose or get_glucose_stats; the agent must infer that from names alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.