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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds valuable behavior: it is read-only, and it warns not to restate currency or assume amounts match Invio's. This goes beyond annotations and sets correct expectations about data fidelity. No contradictions.

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 with high information density. The core purpose is front-loaded, and the caveats about ID source and currency are concise. It is not overly long, though the dash-separated clauses could be slightly more readable, but it earns its place with no fluff.

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 get-by-id tool with no output schema, the description adequately covers what the agent gets (full detail, line items), how to obtain the ID, and critical data-handling warnings. It does not cover error cases or pagination, but that is less critical for a single-record retrieval. Overall it is sufficiently 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 covers organisation with a description but not creditNoteId. The description compensates for creditNoteId by specifying it must be a Xero CreditNoteID (GUID) from list_xero_credit_notes, not an Invio id. This adds meaningful semantic context beyond the schema's format field. With 50% schema coverage, the description carries the missing weight.

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 opens with a specific verb+resource: 'Full detail on one Xero credit note, including line items'. It clearly distinguishes from sibling list_xero_credit_notes (which returns summaries) and get_xero_invoice (different document type). The scope is unambiguous.

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 explicitly states the ID must come from list_xero_credit_notes and never an Invio id, giving a clear sourcing rule. It also implies use when you need full detail (including line items) of a single credit note, which separates it from list tools. The currency warning further guides correct usage without ambiguity.

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