List sources in a scene

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

Annotations already declare readOnlyHint=true, so the safety profile is known. The description adds behavioral context by noting the default to the active scene and specifying the exact output fields (e.g., per-canvas transform, crop/shape/effects applied). This goes beyond the annotation without contradicting it.

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 two sentences with no filler. The first sentence delivers the main action and output; the second provides usage. Every phrase earns its place, making it a model of concise clarity.

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 low-complexity tool with one optional parameter, the description covers the output fields and typical use cases. It doesn't mention error conditions or pagination, but these are not critical for a read-only list operation. The sibling tool set further contextualizes its role.

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?

The input schema fully describes the single parameter scene_id with its default behavior (100% coverage). The description merely restates 'defaults to the active scene,' adding no new information about parameter syntax or behavior 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 opens with a specific verb and resource: 'List the sources in a scene.' It enumerates the exact output fields (ids, types, visibility, per-canvas transform, crop/shape/effects), making it distinct from sibling tools like get_scenes. It also connects to set_source_* calls, clarifying its role.

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 explicitly says 'Use to find source_ids for set_source_* calls, or to see the current layout,' providing concrete usage scenarios. It doesn't mention alternatives or when not to use it, so it earns a 4 rather than a 5.

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