Retrieve a case by ID to inspect its status, outcome, owner, custom attributes, and linked runs, newest first (up to 100).
Get a case by id, including its linked runs (newest first, capped at 100). Use to inspect status, outcome, owner, custom_attrs, and the runs the case has accumulated.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | Case id, e.g. "case_abc123". |
Changes observed during successful MCP inspections.
v0.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond the readOnlyHint annotation, the description discloses that linked runs are included, ordered newest first, and capped at 100. This is useful behavioral context about response content and limits. 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?
Two sentences with no filler. The first sentence front-loads the verb, resource, and key behavioral detail (runs, newest first, cap). The second sentence tells the agent what to inspect, earning its place.
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 no output schema, the description compensates by listing key inspectable fields (status, outcome, owner, custom_attrs) and the runs behavior. It specifies the run cap and ordering, which are essential return semantics. Minor omissions like not-found handling or run pagination are acceptable for a simple getter.
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 parameter 'id' with a complete description including an example ('case_abc123'), so schema coverage is 100%. The description does not add additional parameter-specific guidance beyond restating 'by id', which is already evident.
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 uses a specific verb 'Get' and resource 'a case by id', and distinguishes itself from siblings like invariance_case_list and invariance_run_get by noting it also returns the case's linked runs. The 'newest first, capped at 100' detail further scopes the operation.
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 phrase 'Use to inspect status, outcome, owner, custom_attrs, and the runs' gives clear context for when to use this tool. It doesn't explicitly name alternatives or exclusions, so it stops short of the highest tier, but the intended use case is well conveyed.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.