create_mortise_tenon

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

With no annotations provided, the description carries the full burden and does well: it discloses the failure mode (non-zero 'failed' means cuts did not apply, likely non-manifold geometry), tells the agent how to verify (bbox_mm), and states the geometric precondition. It does not mention permissions, reversibility, or whether the operation is destructive/undoable.

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-loaded with the action, then units/scaling, then the precondition, then a labeled 'Returns' block. No filler sentences; each line (units, offsets, defaults, precondition, return contract) earns 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?

For an 8-parameter geometry mutation with no annotations, the description covers units, offset semantics, default scaling, a precondition, and failure interpretation. An output schema exists, so the added 'Returns' detail is a bonus rather than a necessity, and the only real gap is the absence of any undo/reversibility or permission note.

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%, so the baseline is 3, but the description adds genuine meaning beyond the schema: all dimensions are in millimeters, offsets shift relative to the board face's center, and the defaults are calibrated for ~100 mm boards. That contextual sizing information is not derivable from the schema alone.

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 ('Create a mortise-and-tenon joint between two boards') and implicitly distinguishes itself from sibling joint creators (create_finger_joint, create_dovetail) by naming the joint type. An agent can tell which joint operation to call without opening any schema.

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?

Provides a real precondition ('The two boards must already touch/overlap along the joint axis'), which is useful usage context. However, it gives no guidance on when to choose this over the other joint-creating siblings or what to do when the precondition fails. Adequate but with a clear gap.

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