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

No annotations are provided, so the description carries the full behavioral burden, and it discloses nothing: not which retracement levels are returned (0.236/0.382/0.5/0.618?), not whether the operation is pure computation, nor any error behavior. With no annotations and no output schema, the agent is left entirely uninformed.

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 single sentence is short but wastes its entire length duplicating the title, which is under-specification rather than conciseness. No front-loaded value is delivered.

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?

For a computational tool with no annotations and no output schema, the description should explain what is computed and what the return value contains — it does neither. An agent cannot know what calling this tool produces.

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%, so the baseline is 3 even though the description adds no parameter meaning at all. The description does not clarify whether 'low' and 'high' are prices, time values, or anything else, nor why strings are used — but the rubric sets the baseline at 3 when the schema already documents the parameters.

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 is a verbatim duplication of the tool title ('Fibonacci Retracement: Fibonacci Retracement'), which is the textbook definition of a tautology. It does not state an action or outcome, and it does not differentiate this tool from the many Fibonacci siblings (x402-fibonacci, x402-fibonacci-index, x402-fibonacci-n, x402-fibonacci-series). Only the name's implicit domain knowledge lets an agent guess it derives retracement levels.

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?

There is no guidance whatsoever on when to use this tool rather than x402-fibonacci-series or x402-fibonacci-index, and no prerequisites or context are stated. Nothing tells the agent what inputs low/high are meant to represent.

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