set_locator

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

With no annotations provided, the description carries the full burden. It discloses the idempotent update behavior ('If a locator already exists at this position, its name is updated.') and implies mutability. It lacks details on permissions or side effects, but for a simple tool this covers essential behavior.

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 well-structured and appropriately sized: a clear opening sentence, a usage hint, a behavioral note, and a brief parameter list. Every sentence adds value without redundancy.

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?

Given the tool's simplicity (2 required parameters) and absence of output schema, the description covers all essential aspects: purpose, parameter meanings, a concrete usage rule, and update semantics. It is sufficiently complete for an agent to invoke confidently.

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 provides no descriptions for the parameters, so the description steps in with meaningful semantics: position is defined as 'Beat position (0 = start of song)' and name as 'Label for the locator (e.g. "Drop 1")'. This fully compensates for the schema's lack of annotations.

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 action ('Add or update a named locator') and specifies the exact resource ('at a specific beat position on the Arrangement timeline'). It distinguishes itself from sibling tools like clear_locators by describing the inverse operation.

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 explicit use cases with section label examples ('Intro', 'Drop 1', etc.) and states what happens when a locator already exists. It does not mention alternatives or when not to use it, but the context is clear enough for an agent to select it appropriately.

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