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

Annotations already cover safety (readOnly, idempotent, non-destructive), yet the description adds substantial non-structured behavior: the four outcome states, the polling cue on 'pending', and the critical interpretation rule that 'not-found' means 'not indexed yet, never failed'. It also discloses payment mechanics (x402, x-credit-token, 1 free call/day, no API key), which the annotations cannot convey.

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?

Front-loaded with the agent's actual question ('Did the cross-chain transfer land?') and the core alternative up front. It is dense with useful clauses but the tail (pricing, free tier, 'Not financial advice') adds length, though the pricing detail is actionable for x402 invocation.

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 values need no elaboration, and the annotations carry the safety profile. The description nonetheless completes the picture with trigger context, the sibling relationship, outcome semantics, and payment requirements, leaving nothing an agent needs before calling it.

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 the baseline is 3, but the description adds rationale beyond the schema: it reiterates txHash as required and explains that passing from/to yields 'a faster lookup'. Minor blemish: it lists 'bridge' as a passable optional field, but no such parameter exists in the schema, which could momentarily mislead.

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+resource ('Track [a cross-chain transfer] by source tx hash') and frames itself as 'the other half of bridge-route', immediately distinguishing it from its closest sibling. An agent can tell what it does and how it relates to bridge_route without opening either 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?

Explains the situation that calls for it ('a bridge takes minutes with funds in flight, and from the source chain alone an agent cannot tell if it completed') and names the complementary tool bridge-route. It stops short of explicit when-not-to-use guidance, but the trigger condition is clear.

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