Inspect a named SWAT+ Fortran derived type to list every field's units, meaning, declaration, and whether it is a scalar or allocatable array.
Every field of a derived type, with units, meaning and declaration -- what a state object like aqu_d actually contains, including whether a component is a scalar or a dimension(:), allocatable array.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | Type name, e.g. aquifer_dynamic |
Changes observed during successful MCP inspections.
v0.1.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it does disclose what the output conveys (units, meaning, declaration, scalar vs allocatable array), which is genuinely helpful. It says nothing about read-only behavior, errors for unknown type names, or lookup scope, leaving real gaps for a no-annotation tool.
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?
One front-loaded sentence that names the resource and enumerates the returned facts with no filler. The em-dash aside is slightly rambling but still earns its place by clarifying the output shape.
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?
No output schema exists, yet the description conveys the essential shape of the result (fields plus units, meaning, declaration, array-ness), and the lone parameter is fully documented. Only error/edge-case behavior is missing, which is minor for an introspection tool.
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% and the single parameter is documented as 'Type name'. The description's concrete example ('aqu_d') reinforces the expected input form, but adds no syntax or naming-convention detail beyond the schema. Baseline 3 is appropriate.
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 verb and resource ('Every field of a derived type') plus the nature of the output (units, meaning, declaration). It is clear what the tool does, but it never distinguishes itself from siblings like module_variable or search_fields, so it stops short of a 5.
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 when-to-use, when-not-to-use, or alternative routing. The example ('what a state object like aqu_d actually contains') hints at the intended context, but the agent gets no signal on how this differs from inspecting a module variable or searching fields.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.