assemble

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

Annotations already flag destructiveHint=true, idempotentHint=false, and openWorldHint=true, so the safety profile is covered. The description adds genuinely new behavioral detail beyond that: partial-application semantics under stop_on_error and the subtle rule that nothing moves only if the FIRST mate fails. This transactional nuance is the kind of context annotations cannot convey.

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?

Purpose is front-loaded, the alternative routing sentence follows immediately, and the args block is terse with no redundant restatement of the name or title. Every sentence 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?

An output schema exists, so return values need no explanation, and the destructive/mutation role is well covered by annotations plus the transactional details. The only shortfall is the undocumented doc_name parameter, which matters for a required argument.

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 carries the full burden and does document three of four parameters, including units for tolerance ('mm'), the default value, and the constraint that mates must be non-empty. It omits any explanation of the required doc_name parameter, leaving one gap.

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?

The description states a specific verb and mechanism ('Snap parts together by matching named anchors in one transaction') and explicitly contrasts itself with the sibling assembly_session for persistent joints. An agent can distinguish it from align_shapes, verify_assembly, and assembly_session 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?

It names the alternative (assembly_session) and the condition that selects it ('For persistent joints'), which is clear routing guidance. It also points to operation_help('assemble') for extended reference, though no other siblings (align_shapes, get_anchors) are addressed.

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