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

With no annotations provided, the description carries the full burden of behavioral disclosure. It clearly states the tool is non-sending ('Never sends — simulation only'), specifies the execution environment (mainnet), and details the return payload (decoded error in plain language, logs, compute units, account changes). It also discloses the cost ($0.02 per call in USDC), which is a key operational condition.

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 compact and well-structured. It front-loads the primary purpose and key safety guarantee, then lists return contents, usage timing, cost, and ends with a direct parameter definition. Every sentence adds value with no redundancy or unnecessary elaboration.

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?

Since there is no output schema, the description must explain return values, which it does thoroughly (error, logs, compute units, account changes). It also covers usage context, cost, and input format. For a single-parameter tool with no annotations, this description is fully sufficient for an agent to select and invoke the tool 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?

The schema only labels the parameter as 'Transaction Base64' with no description. The tool description compensates fully by explaining that transaction_base64 is a 'base64-encoded signed or unsigned Solana transaction.' This provides essential format and content details beyond the schema, making the parameter's meaning clear and actionable.

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 opens with a clear statement of purpose: 'Find out whether your transaction will succeed before you pay for it.' It explicitly names the action (simulate) and the resource (a Solana transaction), and distinguishes itself from sibling tools by being the only simulation-related tool. The phrase 'Never sends — simulation only' further clarifies its role.

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 provides explicit usage guidance: 'Use before submitting any unfamiliar or high-value transaction.' It also warns 'Never sends — simulation only,' which helps the agent avoid misuse. Although no alternative tools are named, the sibling context shows this is a unique simulation capability, so no additional exclusions are needed.

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