Update order

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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=true, and openWorldHint=true. The description adds genuinely non-derived behavior: an address field fully replaces the previous address rather than merging it, which is a partial-overwrite hazard the schema never states (the schema just calls these 'Postal address'). It does not mention permissions, validation failures, or rate limits, but the replacement semantics are the key disclosure and are present.

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, zero filler, with the field scope front-loaded before the update-semantics caveat. Every clause changes how an agent calls the tool.

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 mutation tool with full annotation coverage and no output schema, the description covers what can change and the two non-obvious update rules (partial send, full address replacement). It omits error/edge behavior on a non-existent or completed order, but nothing essential to a correct call is missing.

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?

With 80% schema description coverage the baseline is 3, and the description earns above it by clarifying semantics the schema does not: that updates are partial ('send only what should change') and that no field is required beyond the order identifier. It also signals the email/address/metadata parameter families by name, though the metadata merge-vs-delete rule lives only in the schema.

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 gives a specific verb ('Changes') plus resource ('the order's') and enumerates the exact mutable fields: email, shipping/billing address, and metadata. This scoping implicitly separates it from siblings like complete_order, cancel_order, and get_order without the agent needing to open 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?

'Send only what should change' is a real invocation guideline for a partial-update tool, and it prevents an agent from resending unchanged fields. However, it says nothing about when to choose this tool over alternatives such as complete_order or cancel_order, and lists no prerequisites (e.g. order must exist, must not be cancelled), so usage is only implied rather than contrasted.

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