Modify an active delivery's tip, dropoff instructions, or contact phone. Confirm any tip change with the user first, since tip edits move money.
Update an active delivery's tip, dropoff instructions, or contact phone. Tip changes MOVE MONEY — confirm the new amount with the user first.
| Name | Required | Description | Default |
|---|---|---|---|
| tip | No | ||
| dropoff_instructions | No | ||
| dropoff_phone_number | No | ||
| external_delivery_id | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true, readOnly=false, and non-idempotency, so the safety profile is carried. The description adds a genuinely non-structured behavioral fact: that tip edits move money and require user confirmation. It still omits partial-update semantics (what happens to fields left null) and any error behavior on non-active deliveries.
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?
Two sentences, front-loaded with the action and followed by the highest-risk caveat. Every clause earns its place with no 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?
For a destructive mutation tool with 0% schema coverage and no output schema, the description covers the money-risk dimension well but leaves gaps: partial-update behavior for omitted fields, whether the delivery must be in a specific state, and what the caller gets back. Adequate but not complete.
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 compensate, and it does name three of the four parameters with recognizable meaning. It does not explain the required external_delivery_id, nor any format constraints (tip units/currency, phone number format), leaving part of the parameter burden unmet.
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 (Update) and resource (an active delivery) and enumerates the three mutable fields: tip, dropoff instructions, contact phone. This clearly separates it from read-oriented siblings like track_delivery and terminal operations like cancel_delivery, though no sibling is named explicitly.
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?
It supplies one strong precondition — confirm tip amounts with the user before mutating money — which is real usage guidance. However, it never says when to prefer this over alternatives (e.g., re-dispatch, cancel, or editing via another tool) or when the tool should not be used, apart from the implicit 'active delivery' scope.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.