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

Annotations already declare readOnlyHint=true, and the trailing "Read-only" merely restates that. The useful additions are the data-source disclosure ("from the archive's own index") and the meaning of found:false, but nothing is said about miss handling beyond that flag or about response shape for each address type.

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 mapping outcomes are front-loaded in a single dense clause structure, and the found:false semantics land before the trailing note. The final "Read-only." sentence duplicates the annotation and is the one piece of waste.

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 one-parameter lookup with no output schema, the description covers the input types, the per-type return content, and the not-found sentinel, which is most of what an agent needs. It leaves the exact returned fields implicit and does not distinguish itself from the other Olympia lookup tools.

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% and the pattern already enumerates the three accepted prefixes, so the schema carries parameter validation. The description adds value by saying what each prefix returns (account+public key, originating token, node-key validator), which is slightly above the baseline 3 but does not add format or resolution details.

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 states a specific transformation (Babylon address → its Olympia counterpart) and enumerates outcomes per address prefix (account_rdx1…, resource_rdx1…, validator_rdx1…). It does not name or contrast with the near-siblings find_olympia_address, convert_olympia_address, or olympia_lookup, so sibling differentiation is left to inference.

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?

It gives a clear when-to-use context ("works for every migrated account, signed on Babylon or not") and explains the negative result ("found: false means it has no Olympia past"), which tells the agent not to keep probing. It stops short of explicit exclusions or pointing to the alternative tools for the cases this one does not cover.

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