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

Annotations already establish a safe read (readOnlyHint=true, destructiveHint=false), and the description adds real behavioral context beyond that: a single pinned block read, live pricing from OrbitWan's price table, base-unit string amounts, and the partial-failure contract where the total is null with a failed count. That is strong disclosure of edge-case behavior for a read tool.

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 dense sentences, front-loaded with the core resource and an input, followed by the failure contract. No filler and no restatement of the title.

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?

With no output schema, the description carries the return-value burden and does so adequately: it explains amount encoding (base-unit strings) and the null-total/failed-count behavior. Only the address input format and the relationship to sibling tools remain unaddressed.

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 0% for the single parameter, and the description only says "of an address" without clarifying format (raw hex, tagged handle, or identifier needing resolve_identifier). With unresolved format ambiguity that matters given siblings like find_tagged_addresses, the description fails to compensate for the coverage gap.

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?

"Token balances of an address" states a clear resource (token balances) tied to an input (an address), and the pricing/base-unit detail sharpens what kind of balances these are. It does not explicitly distinguish itself from close siblings like get_address_summary or get_address_positions, so an agent still has to infer which holdings-style read it wants.

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?

There is no when-to-use guidance and no named alternative, despite a crowded get_address_* sibling set (summary, positions, flows, tags). Usage is only implied by the resource name; the description never says when this tool is preferred over get_address_summary or get_address_positions.

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