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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered structurally. The description adds meaningful context beyond them: the server is stateless with respect to accounts and holds no key, which tells the agent the address must come from elsewhere. It omits error behavior for malformed/nonexistent addresses, keeping it from a 5.

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 waste, with the core action stated first and the requirement rationale second. Nothing is padded or repeated from the schema or annotations.

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?

An output schema exists, so return-value explanation is unnecessary, and annotations cover the read-only/idempotent safety profile. For a one-parameter stateless read tool, the description provides everything an agent needs 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 description coverage is 100% for the single 'address' parameter, which already documents the aether1... format and required status. The description reinforces the rationale for why the address is required (no server-side key), but adds no new format, validation, or syntax detail beyond the schema. Baseline 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?

States a specific verb ('Check') and resource ('the balance of an address') and clarifies the return scope ('in both whole units and base units'). It is unambiguously distinct from every sibling (find_services, get_miner_status, get_transaction_status, get_account_authenticators), none of which deals with balances.

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 supplies a precondition ('The address is required: this server has no wallet of its own') but never states when to use this tool versus alternatives or covers any exclusion cases. Usage is only implied by the single required parameter, so this is minimum viable rather than genuinely guiding.

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