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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the agent knows this is a mutating, potentially destructive operation. The description adds partial-update semantics ('leave empty to keep current'), which is genuinely useful behavioral context beyond the annotations, but it does not explain what 'destructive' means here or any auth/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?

Purpose is front-loaded in the first line, followed by a compact Args block. Every line is short and there is no filler, though the docstring format is functional rather than optimally structured.

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 not be explained, and annotations cover the safety profile. Params are fully documented, but the definition is silent on usage context and sibling differentiation, leaving it adequate but not complete for a mutation tool with four siblings in the same namespace.

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 must carry the param burden and it does: all four parameters are documented, and the optional ones add real meaning ('leave empty to keep current') that the bare schema does not convey. The ID params are restated tautologically ('The project ID'), which caps this below 5.

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 ('Update a directory collection'), which is clear enough for an agent to know this modifies an existing directory collection. It does not, however, distinguish itself from sibling update tools like update_directory_field, update_directory_item, or update_commerce_collection beyond the resource name.

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?

There is no guidance on when to use this tool versus alternatives, no prerequisites (e.g. that the collection must already exist), and no mention of what happens on partial updates beyond the inline param notes. The agent must infer all of this.

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