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

Annotations already declare readOnlyHint and openWorldHint, and the description adds genuinely new behavioral context: amounts and currency are as Xero stored them and must not be restated or assumed to match Invio's. It does not cover failure behavior (e.g., not-found or cross-org access), which keeps it short of 5.

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, front-loaded with what is returned, then the ID constraint, then the currency caveat. Every sentence carries decision-relevant information, though the currency warning is slightly verbose.

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?

No output schema exists, so the description correctly states what is returned (full detail plus line items) and pre-empts the main downstream misinterpretation about currency and amounts. Missing only edge-case behavior such as not-found handling or multi-org ambiguity.

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?

At 50% schema coverage the description must compensate, and it does for creditNoteId by naming the exact provenance and format (Xero CreditNoteID GUID from list_xero_credit_notes, never an Invio id). The organisation parameter's conditional multi-org rule lives only in the schema, so the description does not fully close 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 and resource ('Full detail on one Xero credit note') plus the scope it returns ('including line items'), which separates it cleanly from list_xero_credit_notes and get_xero_invoice. An agent knows exactly what it gets back.

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?

Explicitly routes the agent to list_xero_credit_notes as the source of the ID and warns that an Invio id will not work, which is the main misuse failure mode. No explicit 'when not to use' or comparison to sibling getters like get_xero_quote, but the context is clear enough to select correctly.

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