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

The annotations already declare readOnlyHint=true and openWorldHint=true, so the description's commitment to read-only behavior is consistent. It adds the useful detail that return data is hex-encoded, but does not disclose potential revert behavior, block-tag handling, or any network-specific quirks beyond the schema.

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 description is two concise sentences, front-loaded with the action ('Execute a read-only smart contract call') and then a clear outcome ('Returns the hex-encoded return data'). Every word earns its place; no wasted text or redundant repetition of the schema.

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 simple read-only call with full schema coverage and readOnly annotations, the description is mostly complete. It lacks an explicit pointer to related decode tools (e.g., mezo_decode_return) that would help the agent interpret the hex output, but this is a minor gap that does not hinder basic usage.

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?

The input schema covers 100% of the parameters with detailed descriptions, so the baseline is 3. The tool description adds no parameter-specific meaning beyond what the schema already provides; it only mentions returning hex data, not the parameters themselves.

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 clearly states the tool executes a read-only smart contract call on Mezo and returns hex-encoded data. It distinguishes from transaction-sending tools, but does not explicitly differentiate from the very similar sibling 'mezo_testnet_call' or the generic 'eth_call' beyond the network name in the tool name.

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 phrase 'Use this to read contract state without sending a transaction' provides a clear usage context. However, it does not mention alternative tools like mezo_multicall for batching calls or the decode siblings for processing the returned data, so the guidance is useful but not fully explicit about exclusions or alternatives.

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