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

Annotations only provide openWorldHint=false and destructiveHint=false, so the description carries the behavioral burden. It discloses important runtime behavior: the server resolves collection SKUs internally, and in cases of no selfie or gender mismatch the response itself shows an upload/onboarding widget. It also instructs the agent to wait for the user to finish the widget, preventing wasteful workarounds.

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 description is longer than average but every sentence carries load: invocation, parameter choice, fallback behavior, and handling of the no-selfie widget. It is front-loaded with the core purpose and then flows naturally into operational details, with only minor redundancy against the schema's parameter descriptions.

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?

This tool has three required parameters, no output schema, and sparse annotations, yet the description covers correct invocation, ambiguity resolution, and edge-case handling (missing selfie, gender mismatch, widget flow). It also preemptively warns against chasing workaround tools, making it complete for an agent selecting and invoking this tool.

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. The description adds meaningful semantics beyond the schema: exact mutual exclusivity ('Provide exactly one of the two'), the explicit empty-string placeholder, and the fallback that a collection name passed as sku will still be recognized by the server. This goes beyond the schema's per-parameter notes.

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 opens with a specific verb and resource: 'Initiate a virtual try-on for one or more products.' It clearly distinguishes the two modes (single product via sku, multiple products via collection_name) and differentiates from siblings by referencing render_mix_and_match and get_mix_and_match as sources of collections.

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 gives explicit when-to-use guidance: pass sku for a single product, collection_name for an outfit, provide exactly one of the two, and even offers a fallback rule ('if you're not sure which one you have, pass it as sku'). It also gives explicit when-not-to-use guidance: do not call this tool again or call get_selfie/request_user_selfie when the response shows a widget.

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