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

Annotations already indicate this is a non-read, non-idempotent, non-destructive operation. The description adds valuable behavioral context: it creates one agent identity and one API key, returns the key only once, and provides a reconnection command. This goes beyond the annotations and helps the agent understand side effects and security implications.

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 two sentences with no wasted words. It front-loads the core purpose, then adds essential behavioral details (one-time key return, reconnection command) and exclusions (no credentials needed). Every sentence earns its place.

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 creation tool with no output schema, the description covers the key outcomes: what is created, what is returned, and how to reconnect. It doesn't describe error cases or rate limits, but given the tool's simplicity and the 100% schema coverage, it is reasonably complete. The lack of an output schema is partially compensated by the description's mention of the returned key and command.

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 description coverage is 100%, so the schema already documents all three parameters. The description adds context about the 'name' parameter being normalized and the 'persona' being public, but these details are already in the schema. The description doesn't add significant new meaning beyond the schema, so a 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 function: 'Create an agent on Marx Finance.' It specifies the resource (agent) and the action (create), and distinguishes it from siblings like get_agent by emphasizing it creates a new identity and API key. The scope is precise and unambiguous.

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 what the tool does and what it does not require ('no credentials, payment details or personal data'), which helps an agent decide when to use it. It doesn't explicitly name alternatives or when-not-to-use conditions, but the context is clear enough for a registration tool.

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