Draws a polygon from coordinate points in a FEMM model, connecting nodes and closing the loop by default, then returns its vertex centroid for use as a block label.
Polygon through [[x, y], ...]: nodes + segments, closed back to the first point by default. Returns the vertex centroid (a block-label candidate only if the polygon is convex).
| Name | Required | Description | Default |
|---|---|---|---|
| closed | No | ||
| points | Yes | ||
| session | No | main |
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. It discloses genuinely useful behavior beyond the schema: that nodes and segments are created, closure is applied by default, and the return is the vertex centroid with a convexity caveat for block labels. It omits session/permission context and whether existing geometry is affected.
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 tight sentences, front-loaded with the most important detail (the points structure) and no filler. Slightly dense with the parenthetical caveat but nothing wasteful.
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 three-parameter drawing tool with no output schema and no annotations, the description covers the input format, default closure, and return value, which is adequate. It still leaves session handling and any side effects on existing document geometry unaddressed.
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 usefully explains the points format ([[x, y], ...]) and ties 'closed back to the first point by default' to the closed parameter, but leaves the session parameter entirely unexplained.
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 (draw) and resource (polygon) plus the concrete effect of creating nodes + segments. It distinguishes itself from femm_draw_rectangle/circle by being point-driven, but never explicitly contrasts with femm_draw_polyline or femm_add_segments, so sibling differentiation is only implied.
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?
No statement of when to use this versus the many alternatives (femm_draw_polyline, femm_draw_rectangle, femm_add_nodes/add_segments). The only usable cue is the implicit 'closed by default' behavior, which is not framed as guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.