get_num_uv_islands

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

Annotations already declare the safe read-only, idempotent, non-destructive profile, so the description's main added value is the return contract. Naming is_valid_uv_channel in the return tuple usefully signals that an out-of-range channel is reported rather than raising an error.

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?

Two short sentences, purpose front-loaded before the return shape, with no filler. Efficient for a simple getter, though the return line is the only content beyond the headline.

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 read with no output schema, the description covers intent plus the returned fields, which is exactly what an agent needs. Only the channel-validity semantics of the return value could be spelled out further.

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 100%, so actor_name and uv_channel are already documented with types and required status. The description confirms uv_channel refers to a UV channel but adds no format, range, or indexing-base detail 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?

States a precise verb and resource: count of UV islands within a specified UV channel of an actor. This is distinguishable from nearby siblings such as get_num_connected_islands and get_mesh_uv_channel_count by the term 'UV islands', though the description never explicitly routes between them.

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?

No when-to-use, prerequisites, or alternative-tool guidance. The agent must infer that this is a read-only inspection call and guess whether list_uv_channels or get_uv_health_report is the better starting point.

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