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

Beyond the readOnlyHint=false mutation flag, the description discloses that real signed webhooks fire to the seller's webhookUrl, the exact lifecycle effects per event (e.g., deposit paid triggers goal.deposit_paid plus goal.subscription_created for subscriptions), a specific failure mode (ALREADY_FUNDED when the current period is paid), and post-state ('the goal stays SAVING'). This is rich behavioral context an agent cannot get from annotations alone.

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 most important fact — instant lifecycle transition with real webhook delivery — is front-loaded, and every parenthetical carries event-specific detail. It is dense and somewhat run-on, but little could be removed without losing behavioral signal.

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 mutating simulation tool with no output schema, the description covers mechanics, per-event effects, failure modes, and sequencing. The one gap is what the call returns (e.g., resulting goal state or webhook delivery id), which would help an agent verify the simulation.

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 80%, but the description adds substantial meaning beyond the enum: it explains the consequence of each event value, clarifies the default $3 round-up chunk for collect, and notes when reversal=true selects the clawback path. This goes well past the terse schema field descriptions.

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 ('moves a sandbox goal through its lifecycle instantly') and resource, and immediately clarifies the key mechanic: each event sends the real signed webhook to the seller's webhookUrl. This clearly distinguishes it from siblings like create_test_goal and cancel_test_goal, which set up or tear down goals rather than driving them through lifecycle transitions.

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 per-event breakdown (confirm, collect, complete, payment_failed, expire) tells the agent which event maps to which real-world scenario, and 'Confirm first' gives explicit sequencing guidance. It doesn't explicitly state when *not* to use it versus alternatives, but the sandbox-simulation scope is unambiguous.

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