Add images to a moodboard

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

Annotations already flag mutation and non-idempotency; the description adds useful behavior: urls are limited to what the account can reach, and added images become reusable via a moodboard title on later generations. No contradiction with annotations.

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 compact, front-loaded with the core operation, and each sentence contributes useful information about input modes or downstream reuse. No filler or schema repetition.

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?

Together with the fully described schema, the definition covers the required moodboard, the two source modes, and the role of indexes. It doesn't describe return values or combined job_id+urls behavior, but these are minor for a simple add operation with no output schema.

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 covers all four parameters, and the description adds mode semantics beyond the schema: job_id means this job's renders, urls means arbitrary account-reachable images, and indexes are an optional narrowing mechanism. This helps an agent choose between the sources.

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 action (add images to a moodboard) and immediately clarifies the two input modes: job_id for generated renders and urls for direct URLs. This clearly distinguishes the tool from siblings like remove_from_moodboard and create_moodboard.

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 gives explicit guidance for when to use job_id vs urls and explains that indexes narrow a job's renders. It lacks explicit exclusions or named alternatives, but the use case is clear enough for an agent to select it correctly.

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