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

With no annotations provided, the description carries the full burden, and it does so thoroughly. It discloses that saving an already-saved address renames the entry, making the operation safe to retry. It warns that a name is a label, not an instruction, and advises confirming the resolved address before sending. These are meaningful behavioral insights beyond what schemas could convey.

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 longer than average but every section adds value: the rename semantics, the safety guidance, and the retry behavior. It is front-loaded with a one-line purpose, then expands into necessary caveats. A few sentences could be tightened, but the structure is logical and not padded.

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?

Given three parameters, no output schema, and no annotations, the description covers the operation's purpose, usage, key behavioral nuances, and parameter meaning. It does not explicitly mention what the tool returns (e.g., success message or entry), but the emphasis on rename behavior and retry safety largely compensates. This is sufficient for an agent to invoke it correctly.

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%, so the baseline is 3, but the description adds valuable semantic context: the address is the entry's key (so re-saving renames), the name is capped at 60 characters server-side, and no user parameter exists. It clarifies the auth_token's conditional use better than a plain schema note, tying it to header absence.

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 opens with a specific verb and resource: 'Save or rename a recipient.' It clearly identifies the address book as the target and distinguishes it from sibling tools like delete_address_book_entry and list_address_book by emphasizing the save/rename operation on a single entry.

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 the intended use case: resolving human-friendly names to addresses for later actions. It explicitly contrasts with agentWalletTransfer, stating that transfer takes an address and deliberately does not accept a name. While it doesn't explicitly say 'use this when you need to persist a name', the context and alternative are clear. It also notes that it operates on the authenticated account's own book with no user parameter.

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