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

With only readOnlyHint=true available, the description carries extra weight and delivers: it discloses the data source ('reads the Gateway'), the recovery mechanism (extract secp256k1 public key from the account's last 10 withdrawal signatures and keep the one that derives the address), and the precise meaning of each failure result. This is behavior an agent genuinely cannot infer from annotations or schema.

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?

Purpose, mechanism, precondition and result semantics are ordered from most to least immediately useful, and every clause adds information — there is no filler or repetition of the schema.

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 covers the important part — the shape of unsuccessful results ('found: false' plus a reason) — but it never states what a successful return contains beyond the implication of 'found'. Given the non-obvious grunt work this tool performs, some indication of the success payload would be useful.

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 both parameters are already documented, and the description adds no format or syntax detail beyond clarifying that babylonAddress is a Babylon (hashed-key) account rather than an Olympia one. Baseline 3 is appropriate when the schema does the heavy lifting.

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 — 'finds the legacy Olympia address (rdx1…) behind a Babylon account' — and immediately positions itself relative to the sibling convert_olympia_address as its reverse. An agent can distinguish this from the forward converter and from inspect_address without opening any 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?

Sets a hard precondition ('only works once the account has signed a Babylon transaction') and explains what the failure outcomes mean for usage decisions — 'no-transactions' does not mean non-legacy. It does not explicitly recommend an alternative when the precondition fails (e.g. use convert_olympia_address or inspect_address instead), which keeps it just short of a 5.

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