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

Annotations already establish that this is a read-only, idempotent, non-destructive operation. The description adds meaningful behavioral context by explaining the retention window and that both `replacements` and `replaces` are null when no history is known.

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 text is short, front-loaded with the core purpose, and every sentence adds useful information: null behavior, retention scope, docs link, and REST operation.

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 the description need not document return structure, and annotations cover safety. The description handles the main edge case, but it could better distinguish this tool from the other RBF-related siblings.

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?

There is only one parameter, `txid`, and the description only implies it through the REST path. The schema definition provides the hash format, pattern, and examples, so parameter meaning is adequate overall, but the description itself adds little 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?

The description gives a specific verb and resource: it returns the RBF replacement tree for a transaction. That is clear, but it does not explain how this differs from siblings such as get_fullrbf_replacements or get_replacements.

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?

Usage is implied: call this when you need the RBF history of a specific transaction. The null-result condition is useful, but there is no explicit guidance on when to use this versus the other replacement-related tools.

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