insert_usd_sublayer

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

Annotations already declare readOnlyHint=false and idempotentHint=true, so the mutation/idempotency profile is covered. The description goes further by spelling out the exact idempotent outcome ('returns already_present without erroring') and, with no output schema present, enumerates the full return shape including index, new_count, saved, and errors. The remaining gap is that it does not say whether this persists to disk automatically.

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 sentences, front-loaded with the action and scope, followed by the idempotency guarantee. The Returns block is dense but earns its place because there is no output schema. 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?

For a 3-parameter mutation tool with full schema coverage and safety annotations, the description supplies the missing return contract and idempotency semantics. It omits preconditions (stage must exist / be open) and whether a save occurs, which the presence of 'saved' in the return payload makes relevant.

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% (index semantics, stage_name, and sublayer_path with example forms are all documented in the schema). The description adds a partial hint about the sublayer_path concept but nothing about index or the prepend/append behavior. Baseline 3 is appropriate when the schema carries the parameter burden.

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 resource with scope: 'Add a sublayer path to the stage's root layer's composition stack.' That is far more precise than the bare name and implies the root-layer target. It stops short of naming the natural sibling (remove_usd_sublayer) or distinguishing itself from other layer-stack mutations like mute_usd_layer, so sibling differentiation is left to the verb.

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?

Usage is implied: the parenthetical tells the agent that re-running with the same path is safe because it returns already_present without erroring. However, it never states prerequisites (whether the stage must be open, which edit target is affected) or when to prefer list_usd_stage_layers / remove_usd_sublayer instead. Adequate but with clear gaps.

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