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

With no annotations, the description carries the burden alone. It discloses that there may be multiple accounts per channel and that send-capability is evaluated at call time ('whether it can send right now'), which is useful behavioral context, but it says nothing about ordering, pagination, or what happens if no accounts are linked.

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 tight sentences: identity and scope first, then the practical note about how other tools consume the result. No filler and nothing buried at the end.

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?

There is no output schema, so the description must explain returns, and it does name the two relevant fields and their meaning. It is nearly complete for a trivial zero-parameter list tool, with only edge-case behavior (empty list, ordering) left unstated.

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 the baseline is 4 and there is nothing for the description to compensate for. The description instead uses the space to clarify output field semantics (`account`, `connection_id`), which is a reasonable substitute.

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 names a specific verb and resource ('List the messaging accounts linked to Parley') and adds scope detail that separates it from siblings: several accounts can exist per channel, e.g. personal vs work WhatsApp, which distinguishes it from list_channels. It also states what each entry contains (the `account` number and whether it can send right now).

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 gives clear downstream context: 'Other tools take `connection_id`: this id, or simply the account's number,' which tells the agent when this tool is a prerequisite. There are no explicit exclusions, e.g. it never says how this differs from connect or connection_status, so it stops short of a full when/when-not statement.

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