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

Annotations already establish readOnly, idempotent, and non-destructive behavior, so the bar is lower. The description does add real nuance — invoice contents are "immutable" while the payment balance is a "current reported" figure, warning that balance is live rather than part of the snapshot — but it says nothing about permission requirements for shared businesses or behavior on a missing/invalid ID.

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?

A single front-loaded sentence that packs the resource, the immutability qualifier, and the returned fields with zero redundant wording.

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?

With no output schema, the description carries the burden of describing return contents and does so by naming four distinct data groups. It is nearly complete for a two-parameter read tool, missing only edge-case behavior and the ID sourcing hint that already lives in the schema.

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 only 50%, and only business_id carries schema text (omit for your own business, use businesses_list for shared IDs). The description adds nothing about invoice_id formatting or scoping, so it fails to compensate for the uncovered parameter.

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 ("Read") and enumerates the returned resources (invoice contents, source allocations, tax details, payment balance), which clearly separates it from the list/aggregate siblings such as invoices_list and invoice_check. Sibling differentiation is implicit via the singular resource rather than named alternatives.

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?

Usage is implied by the verb "Read" plus the singular invoice resource, so an agent can infer this is the per-invoice detail lookup. However, it never states when to prefer it over invoice_check, invoices_list, or invoice_cancel_draft, nor does it note any precondition such as the invoice needing to exist.

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