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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds useful context by explaining that envelopes are created, topped up, and revoked by the principal in the dashboard, which reinforces why this is read-only for the agent. It does not mention pagination or ordering, but that is a minor gap.

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 no filler. The first sentence names the resource and scope, and the second explains the entry contents and ownership context. Every sentence earns its place, and key information is front-loaded.

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 parameterless list operation with rich annotations and no output schema, the description is complete: it states what is listed, for whom, what each entry contains, and the read-only nature. Nothing an agent needs to decide whether to call it is missing.

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 has zero parameters, so the description carries no parameter-documentation burden; the baseline of 4 applies. The description instead adds value by detailing what each returned entry contains, such as balance, scope, validity, and caps.

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 begins with a specific verb and resource: 'List the active and historical payment envelopes the calling agent instance can draw against.' It clearly distinguishes this from a single-envelope lookup by framing it as a list and defining the scope of what is returned.

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?

The description gives clear context: use this when you need an overview of active and historical payment envelopes, including balances, validity, and caps. It does not explicitly call out an alternative like envelopes_get or state when not to use this tool, so it stops short of full 5.

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