get_num_open_border_edges

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

Annotations already carry the read-only/idempotent/non-destructive profile, so the bar is lower. The description adds genuinely new context: the mesh is 'live' in the editor world, the result semantics (0 = closed), and a naming caveat about actor_name. It doesn't discuss failure modes (e.g. missing actor), which keeps it from a 5.

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?

Front-loads the core action, then the interpretive rule, then the sibling pointer, then the return shape. Every clause earns its place with no filler.

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, so the inline 'Returns: { actor_name, num_open_border_edges }' is necessary and present. Combined with the result interpretation and alternative pointer, an agent has everything needed to call and interpret this read-only 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 description coverage is 100%, so the schema already documents actor_name fully. The description's naming note ('Reply actor_name is the component name, not the actor label') concerns the returned value rather than the input parameter, adding only marginal input semantics. Baseline 3 applies.

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 ('Count the open boundary edges') and even defines the concept inline ('edges with a single adjacent triangle'), scoping it to a DynamicMeshActor's live dynamic mesh. An agent can immediately distinguish it from siblings like get_mesh_triangle_count or get_mesh_is_closed.

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?

Explicitly names the alternative for adjacent needs ('get the loops with get_mesh_open_border_loops') and gives an interpretive rule for the output ('0 means the mesh is closed'). It stops short of stating when-not to use it, but the routing context is clear.

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