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

Goes well beyond the annotations by disclosing side effects: the cancel is confirmed before the row flips, any linked charge is released, and a terminal job yields a 422 no-op-reject. The 422-on-terminal behavior sits consistently with idempotentHint=true (no state change on repeat). Auth/permission requirements and the response shape are still unspecified.

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 tight sentences with no filler; the action and scope come first, then prerequisites, then side effects and error semantics. Every clause carries decision-relevant information.

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-param mutation with no output schema, it covers prerequisites, side effects, and failure semantics adequately. It omits permission/precondition requirements and confirms only implicitly that no data is destroyed.

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 coverage is 100%, but the schema descriptions are near-empty ('projectId (path).'), so the description carries real weight by naming both required params and telling the agent that composeJobId originates from the compose tool. It adds no format or validity detail beyond that.

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?

Starts with a specific verb+resource ('Cancel an in-flight compose job') and immediately disambiguates it from the cluster of cancel_* siblings with the parenthetical use case 'stop a runaway/mis-priced ensemble'. An agent can distinguish it from cancel_job, cancel_render and cancel_export without opening any schema.

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?

States the trigger context ('runaway/mis-priced ensemble') and where the required ids come from ('from compose'), which is real routing guidance. It stops short of explicitly naming the alternative cancel tools for other job types, so an agent must infer that renders/exports go elsewhere.

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