femm_draw_circle

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden. It usefully discloses the internal decomposition (four 90-degree arcs, node placement at cardinal angles), which is real behavioral context. However it says nothing about permissions, undo/reversibility, selection state effects, or how the result interacts with existing geometry — notable gaps for a mutation tool with zero annotation coverage.

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 with the core construction detail front-loaded and the alternative routing last. Dense but every sentence earns its place; the parenthetical node angles are arguably more than needed but genuinely informative.

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 geometry-drawing tool with no output schema and no annotations, the definition supplies the essentials: what is created, how it is discretised, and when to prefer a sibling. The single unexplained 'session' parameter is a minor residual gap.

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 0%, so the description must compensate, and it largely does: r is the radius, cx/cy the centre, and maxseg is defined as 'arc discretisation in degrees'. Only the session parameter (default 'main') is left undocumented in both schema and description.

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?

Specific verb (draw) plus resource (circle) with precise construction semantics: 'Full circle of radius r around (cx, cy) as four 90-degree arcs (nodes at 0/90/180/270 deg).' It distinguishes itself from the sibling femm_add_arcs, so an agent can choose correctly without opening schemas.

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?

Gives an explicit alternative with its condition: 'For a half circle in axi models, use femm_add_arcs.' That is clear routing, though it covers only one exclusion and says nothing about when a circle should be drawn vs a rectangle or polygon approximation.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.