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

With no annotations available, the description carries the full burden of behavioral disclosure. It does so well by stating that adding creates an immutable, self-contained copy of the whole subtree plus asset bytes, and that later edits or deletions of the source do not affect existing copies. This goes beyond a simple 'adds to collection' statement, though it does not cover every possible side effect such as permission requirements.

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?

The core action and accepted inputs are front-loaded in the first sentence, with subsequent sentences adding important behavior about immutability, workspace sharing, and naming. It is long, but every sentence earns its place by clarifying usage and consequences rather than repeating schema data.

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 two-parameter tool with no output schema, the description is complete: it explains what to pass, where the layer appears, how copies behave, how teammates can use it, and what prerequisite to satisfy first. An agent has enough context to select and invoke the tool correctly.

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?

Both parameters are already fully described in the schema at 100% coverage, so the baseline is 3. The main description reinforces that elementId can be a leaf or group.<id> and that projectId selects the existing project to mutate, but it does not add substantial new meaning beyond the schema.

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 clearly states the action: 'Add a layer to the user's reusable Collection,' and specifies what kinds of element IDs are accepted (leaf or group.<id>). It also differentiates itself from related siblings by explicitly mentioning list_collection and add_from_collection, so the agent understands the exact role of this tool.

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?

The description names the relevant alternatives: list_collection for viewing the collection and add_from_collection for dropping a copy into another project. It also explains when this works (solo projects and workspace projects) and advises renaming layers first with rename_layer/rename_group, giving strong guidance on when and how to use the tool.

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