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

Annotations already cover readOnly/idempotent/non-destructive, so the bar is lower, but the description still adds two traits not in the structured fields: it costs nothing and performs no network/on-chain work, just local format checks. That is genuinely useful for an agent deciding whether to call it. Minor tension with openWorldHint=true, though not a direct contradiction.

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?

A single front-loaded clause with zero waste and the key differentiator ('no on-chain lookups') surfaced early. It is terse to the point of leaving gaps, but from a structure standpoint nothing is 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?

Output schema and rich annotations carry much of the burden, so the definition is close to adequate for a simple 2-param validator. However, it never explains how to fill the required address/chain pair or confirms whether a failure response differs from a thrown error, leaving real gaps for a validation tool.

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 two required parameters, and the description says nothing about what 'chain' or 'address' must contain. It misses the one thing an agent needs: that address format expectations differ per chain (hex for base/ethereum vs base58 for solana).

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 ('format-check') and resource ('a token_check request'), and the parenthetical '(no on-chain lookups)' implicitly distinguishes it from the sibling token_check, which presumably does the real lookups. It stops short of explicitly naming token_check or the other validate_* siblings as the alternative path.

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 word 'Free' plus 'no on-chain lookups' strongly implies 'use this before spending credits on token_check', but the routing is left to inference. No explicit when-to-use, when-not-to-use, or named alternative is given.

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