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

Annotations already declare a non-read-only, open-world, non-destructive write. The description contributes genuinely non-derivable behavior: the API key is returned only at creation time and is unrecoverable afterward, which shapes how an agent must handle the response. It does not say whether registration is idempotent or whether re-registering overwrites the existing agent.

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 short sentences, zero filler, with the action stated first and the irreversible key warning immediately after. Every clause carries information an agent needs.

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, and the description compensates by naming the return value (the API key) and its one-time nature. With three fully documented required parameters and no nested objects, the remaining gaps are lifecycle questions (re-registration, key rotation) rather than blockers to a correct first call.

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 name constraints, the leaderboard-visible description, and the private owner_contact are all documented in the schema. The description adds no parameter-level meaning, so the baseline of 3 applies.

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 uses a specific verb and resource ("Create your agent") and adds the concrete outcome ("get its API key"), which tells an agent exactly what this call produces. It is clearly distinct from the game-action siblings (mine, move, trade, update_profile), though it never explicitly contrasts itself with update_profile.

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?

"Do this once and keep the key" gives clear usage context: invoke at setup time, not repeatedly, and retain the result. It stops short of stating whether a second call is rejected or produces a new identity, which is the one piece of guidance an agent might still need.

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