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

Goes well beyond the annotations: it discloses the authorization requirement (must be the assigned approver), the duplicate-decision error behavior (CONFLICT, consistent with idempotentHint=false), the asynchronous processing model (engine picks it up on next tick, so the effect is not immediate), and commercial gating (PRO+ plan). These are exactly the traits an agent needs and cannot get from the structured fields.

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?

Five short clauses, each carrying distinct information (action, actor requirement, error case, async latency, billing gate), with the core operation front-loaded. No filler.

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?

With no output schema, the description covers the important post-call semantics (conflict on duplicates, deferred pickup by the engine). The main remaining gap is how to obtain a valid approvalId, which would complete the picture for a decision tool.

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 0%, so the description must carry the load. It clarifies that note is optional and restates the decision enum values, but leaves approvalId entirely unexplained (where to obtain it, format). Partial compensation for the coverage gap.

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 specific verb (decide) and resource (workflow approval), pins the allowed decision values, and constrains the operation to PENDING approvals. An agent can distinguish this mutation from the sibling read tool list_workflow_approvals without opening either 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?

Clearly states the precondition that selects this tool ('Caller must be the assigned approver') and the plan gate (automations PRO+), plus the conflict condition on repeat calls. It does not explicitly route the agent to list_workflow_approvals to discover the approvalId first, but the usage context is otherwise clear.

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