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

Annotations mark destructiveHint true, but the description adds context about Bitcoin Lightning payment and no telecom account. It does not fully explain the destructive nature (e.g., cost incurred, irreversibility). No contradiction with annotations.

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 concise (3 sentences), front-loads the core purpose, and includes all necessary context without extra words. Every sentence adds value.

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?

The tool has 5 parameters and no output schema. The description covers the basic operation and prerequisites but does not explain what happens on completion, error cases, or whether it is synchronous/asynchronous. More detail would be beneficial given the lack of output schema.

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 coverage is 100% with descriptions. The description adds minimal extra meaning beyond the schema, such as the mutual exclusivity of 'message' and 'audioUrl' and the requirement for 'durationMinutes' with audioUrl. Baseline 3 is appropriate.

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 clearly states the tool's purpose: 'place an automated phone call to deliver a spoken message or play audio to any number.' It uses a specific verb ('place'), resource ('phone call'), and distinguishes from sibling tools like 'send_sms' or 'ai_call'.

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 explains when to use the tool: 'notifying a human, delivering alerts, or reaching someone who isn't online.' It also mentions the prerequisite of using 'create_payment' with specific parameters. However, it does not explicitly exclude alternative tools or provide when-not-to-use guidance.

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