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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered by structured data. The description adds the underlying endpoint (GET /sources) and the shape of each record, but says nothing about pagination, result size, or account/permission prerequisites.

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 compact sentence plus the endpoint, front-loaded with the resource. Nothing is wasted, though the trailing 'GET /sources' is largely redundant with the tool's own name.

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 parameters and no output schema, the description carries the burden of describing the return values, and it does so at a useful level of abstraction (id, name, type with concrete examples). Only pagination/ordering behavior is left unstated, a minor gap for a small reference list.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The field enumeration (id, name, type) is a small bonus but concerns the response rather than inputs.

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 the exact resource ('order sources available in the account') and even enumerates the returned fields and example types (Allegro, shop, marketplace), which distinguishes it from sibling list tools like list_order_statuses or list_payment_methods. The verb is only implied by 'available' rather than explicitly 'list', which keeps it just short of a 5.

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?

There is no statement of when to use this tool, when not to, or which sibling to prefer. An agent must infer from the sibling names that this is reference data for resolving an order's source rather than, say, integration accounts.

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