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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds the single-record scope and Id-based lookup semantics, but offers no additional behavioral context such as not-found handling, return shape, or connection requirements. Consistent with annotations and adds modest value beyond them.

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 sentence with zero filler; every word carries information. The verb and resource are front-loaded, and the scoping qualifier ('single', 'by Id') immediately follows. Nothing could be cut without losing meaning.

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 simple 2-parameter, read-only point lookup with no nested objects and full schema coverage, the description covers the essentials. The only notable gap is the absence of routing guidance among the large set of vendor/get/search siblings; return-value details are self-evident for a 'Get' tool and no output schema exists.

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 100%, with both id and company fully described in the input schema. The tool description reinforces that lookup is by Id but adds no new parameter meaning, so the baseline of 3 applies.

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 states a specific verb ('Get'), resource ('a single vendor credit'), system ('QuickBooks Online'), and lookup method ('by Id'). The 'single ... by Id' phrasing functionally distinguishes it from search_vendor_credits (criteria-based list lookup) and other vendor-related getters like get_vendor_balance or get_vendor_expenses.

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 context is only implied: the phrase 'by Id' signals that this tool is for point lookups when the vendor credit Id is already known, as opposed to searching. However, it never names alternatives (e.g., search_vendor_credits for finding by criteria) or states any exclusions, leaving the agent to infer the boundary itself.

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