label_join_regions

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

No annotations are provided, so the description carries full behavioral burden. It discloses that labels 'stay where they are' (i.e., labels are preserved), which is useful behavioral context. However, it doesn't mention whether this is destructive to existing clip splits, whether it's reversible, or any permission requirements. For a mutation tool with zero annotation coverage, more transparency would be beneficial.

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?

Three sentences, front-loaded with the primary action. Each sentence adds value: the operation, the inverse relationship, and the operational prerequisites. Compact and readable, though the passive phrasing 'Acts on labeled regions' and 'The labels themselves stay where they are' could be tightened.

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 parameterless tool with no output schema, the description covers the core operation and prerequisites. However, given that no annotations exist, there's no safety/reversibility information. Given the complexity of audio editing and the large sibling set (many other label and edit tools like edit_join, label_cut_regions, label_delete_regions), the description could clarify what distinguishes this from edit_join or label_delete_regions' behaviors.

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?

With 0 parameters and 100% schema description coverage (no properties at all), the description correctly contains no parameter-specific information. The baseline for 0 params is 4. The description appropriately focuses on operational context (selection prerequisites) rather than parameters that don't exist.

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 clearly states the tool's purpose: joining audio clips across labeled regions, with a specific verb ('Join') and resource ('audio clips across every labeled region'). It also explicitly identifies itself as the inverse of label_split_regions, one of its siblings, which aids disambiguation. However, it could be slightly clearer that the operation merges segments per label rather than across all labels.

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 provides specific usage context: it acts on labeled regions within the current selection on selected audio tracks, and explicitly instructs to select audio tracks and time range first ('select the audio tracks and time range first'). It names the inverse sibling tool label_split_regions. However, it doesn't explicitly state when NOT to use it or mention alternatives beyond the inverse.

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