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

With no annotations, the description carries the burden of behavioral disclosure. It mentions 'Reference-grade implementation' and 'wire format normative,' indicating quality and format expectations, but it does not describe return value structure, error conditions, or side effects. The term 'Retrieve' implies read-only, but more detail would be needed for full transparency.

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 highly concise with two sentences. The first sentence states the primary purpose, and the second adds relevant context about implementation grade and wire format. No extraneous information is present, and the key action is front-loaded.

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?

The description is adequate for a simple retrieval tool, but the absence of an output schema means the description should clarify the return format. The phrase 'wire format normative' gives a hint, but it does not describe the proof structure or behavior on invalid inputs. More context could improve completeness.

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 already provides descriptions for both parameters ('0-based node index' and 'Chain identifier'), giving 100% coverage. The description adds no additional parameter semantics beyond that, so the baseline of 3 applies because the schema does the heavy lifting.

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's action: 'Retrieve a Merkle inclusion proof for a specific node in a custody chain (C16).' This is a specific verb+resource construction that distinguishes it from sibling tools like custody_append and custody_verify, which handle different operations.

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 some context about the implementation maturity ('Reference-grade implementation. Wire format normative; production-grade is Layer B'), which hints at use cases but does not explicitly state when to use this tool versus alternatives. It lacks explicit when-to-use or exclusions, so it falls short of clear guidance.

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