Retrieve a metrics JSON object from S3 by providing its key. Get structured metrics for a specific stored run to analyze performance and support monitoring.
Fetch a metrics JSON object by S3 key.
| Name | Required | Description | Default |
|---|---|---|---|
| s3_key | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the burden of disclosing behavior. 'Fetch' implies a read-only operation and 'JSON object' indicates the return type, but there is no mention of error behavior, authentication, or side effects. This is adequate for a simple getter but not richly transparent.
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 short sentence with no filler. The core action and resource are front-loaded, and every word contributes meaning.
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 one-parameter fetch tool, the description covers the essential action and return type, but with no output schema and no annotations, it lacks guidance on error cases, key sourcing, and alternatives. The presence of metrics_list as a sibling highlights the missing usage differentiation.
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 description coverage is 0%, so the description must compensate. It does add meaning by clarifying that s3_key is used to fetch a metrics JSON object. However, it does not explain key format, required structure, or how the key relates to the metrics source beyond the name.
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 states a specific action ('Fetch'), a specific resource ('metrics JSON object'), and the lookup mechanism ('by S3 key'). It clearly differentiates this from sibling tools like metrics_list, which presumably list metrics rather than fetch a single object.
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?
The description implies usage: use this tool when you have an S3 key and need the corresponding metrics JSON object. However, it does not explicitly contrast with metrics_list or other siblings, nor does it state when not to use this tool.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.