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

Annotations already declare readOnly, idempotent and non-destructive, so the bar is lower; the description still adds real value by listing exactly what is observable (mempool vs mined, block, confirmations, spendability, mining pool, reorg contention) and by disclosing the hard limitation that amounts and parties are encrypted. That limitation is the key behavioral fact an agent could otherwise mis-assume, though nothing is said about not-found or unconfirmed-input handling.

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 verb plus resource, followed by a single dense enumeration of return facets and one short clarifying sentence about encrypted data. The list is long but every item is distinct and informative; nothing is filler.

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 burden of describing returns and does so thoroughly across status, block, confirmations, spendability, pool and reorg history, plus the privacy caveat. Minor gaps remain around unknown-hash behavior and whether results are cached or point-in-time.

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% and the schema already gives the 64-character hex format with a worked example, so the description's "64-character hash" phrasing is largely redundant. No additional meaning (e.g., prefix matching, case sensitivity) is contributed beyond the schema.

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?

Names a specific verb and resource ("look up a transaction by its 64-character hash") and immediately enumerates the returned facets, which cleanly separates it from block-oriented siblings like get_block and search_block. An agent can tell what this tool answers without opening the 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?

The lookup key (tx hash) and the questions it answers make the appropriate use case clear, and the explicit statement that amounts/senders/recipients are unavailable steers the agent away from using it for value-transfer questions. It does not, however, name a sibling alternative or state a when-not condition in tool-selection terms.

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