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

The description says "Nothing is read or changed," but annotations declare destructiveHint=true and readOnlyHint=false, creating a direct contradiction about side effects. This is a serious transparency failure for a mutation-shaped tool.

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?

The description is short, but it front-loads billing background that does not help an agent invoke the tool. The key fact, that the tool is unsupported, appears only after irrelevant detail.

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 five undocumented parameters, no output schema, and annotations that conflict with the description, the definition is not complete enough to support correct invocation. The only actionable statement is that the tool is unsupported.

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?

There are five parameters with 0% schema description coverage, including confirm, idempotencyKey, and acknowledgedAmountUsd, and the description explains none of them. It does not compensate for the undocumented schema at all.

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 does not state what start_chat actually does; it mainly explains that chat billing is not wired to MCP and that the tool is unsupported. An agent can infer it is a chat-start placeholder, but the operational purpose is absent.

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 explicitly says the tool is not yet supported, which is useful guidance not to invoke it. However, it does not name alternatives such as start_call, send_message, or get_chat_summary, so routing guidance is incomplete.

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