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

Annotations already declare a non-read-only, non-idempotent, open-world, non-destructive write, and the description adds genuinely new behavioral facts beyond them: the key is shown once and must be kept secret, the same wallet returns the same account with a new key, and no free credit is granted. The only gap is return shape beyond the key, which is minor for a registration tool. Score 3 reflects solid value on top of an already-informative annotation set.

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?

Front-loaded with the step position, then identity, return value, repeat-call semantics, funding caveat, and parameter sourcing — five dense sentences with no filler and no repetition of schema text.

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?

A write tool with no output schema, yet the description covers the auth path, the return value, secret-handling, repeat behavior, and the funding prerequisite. The remaining hole is the required nested agent object's field semantics, which neither schema descriptions nor the prose fully cover.

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 description explains the provenance of message and signature and supplies a default for scopes (["renter","host"]) that the schema itself never states, which is real added meaning. However, the nested 'agent' object — the only required parameter — is never described, and its fields like model, homepage, and operator_contact remain undocumented at 50% schema coverage.

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?

States a specific verb and resource ('Opens an AmpleRun account for this AI agent') plus the concrete outcomes: agent-created tag, verified payout wallet, and an API key returned. The 'Step 2 of 2' framing and the reference to get_agent_account_challenge make it distinguishable from its only sibling without opening either schema.

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?

'Step 2 of 2' plus 'Pass message and signature from get_agent_account_challenge' gives an explicit prerequisite and correct ordering relative to the sibling. It also states a usage constraint ('There is no free credit: renting needs a deposit first') and what repeat calls mean, leaving little to inference.

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