carpe_key_usageRetrieve requests, token counts, and costs per API key over the last 1-90 days, including each key's rail and status, to monitor account usage.
Requests, tokens and cost per API key of the account over the last N days, with each key's rail and status. Free.
| Name | Required | Description | Default |
|---|---|---|---|
| days | No |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations already establish that this is a read-only, idempotent, non-destructive, closed-world operation. The description adds useful context by listing the metrics returned and noting that the call is free, but it does not mention authentication requirements, pagination, or response format details.
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 efficient sentence with the scope, metrics, and cost note front-loaded. Every phrase adds information, and there is no unnecessary wording.
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 simple read-only tool with one optional parameter and no output schema, the description is nearly complete: it explains the grouping, time window, returned metrics, and free status. The main omission is the default lookback behavior when days is not supplied.
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 one optional parameter, days, with 0% description coverage. The description says 'over the last N days,' which gives the parameter meaning, but it does not state the default when days is omitted, so it only partially compensates for the schema gap.
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 clearly states what is returned: requests, tokens, cost, rail, and status per API key over the last N days. It is specific enough to distinguish this from generic account-level usage, but it does not explicitly contrast itself with sibling tools such as carpe_usage_summary or carpe_usage_history.
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?
There is no explicit guidance on when to use this tool versus the many sibling usage and billing tools. The word 'Free' is a useful cost signal, but it does not tell the agent when this per-key view is preferable to carpe_usage_summary or carpe_usage_history.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.