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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds useful context beyond that: it frames the tool as a settlement check and, crucially, enumerates the return payload (confirmations, blockhash, vin_count, up to 12 outputs) even though no output schema exists. It omits rate limits or failure modes for an unknown txid, which keeps it short of a 5.

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?

Four compact sentences with zero filler, front-loaded with the core purpose before usage and return details. Each sentence carries distinct information (purpose, triggers, exclusions, return shape).

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 present, the description compensates by listing the returned fields, and it pairs that with explicit usage boundaries and a single well-documented parameter. An agent has everything needed to select and invoke it 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?

Schema description coverage is 100% and the single txid parameter is fully documented in the schema with a hex pattern. The description adds no syntax or format detail beyond that; per the baseline rule for high schema coverage, 3 is appropriate.

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?

Opens with a specific verb+resource ('Look up one Bitcoin transaction by txid') and immediately scopes it ('the core settlement check'). It explicitly names the two nearest siblings (btc_get_block, btc_get_address) and what they cover instead, so the agent can discriminate without opening any 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?

Contains an explicit 'When to use' clause framed as concrete questions (has the payment arrived, which block, how many confirmations) plus a 'Do not use' clause routing to btc_get_block and btc_get_address. Both the positive trigger and the exclusions are stated, leaving nothing to inference.

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