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

With no annotations, the description carries the burden. It discloses a non-obvious transformation (hourly venues shown as 8-hour equivalent) and the 'tracked crypto symbols' limitation. It does not mention rate limits, return structure, or behavior for invalid slugs, but the disclosed transformation is meaningful behavioral context.

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 entire description is one tightly packed sentence that front-loads the core purpose, then adds the exchange list, unit normalization note, and slug usage. Every phrase earns its place with no repetition or 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?

For a single optional parameter with no output schema, the description covers the two invocation modes, the data source exchanges, the unit conversion, and slug examples. It does not enumerate tracked symbols or detail the output fields, but this is likely sufficient for correct tool selection and invocation.

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 schema only defines slug as a string with maxLength 20 and no description. The tool description compensates by explaining that slug selects one symbol's history and provides concrete examples (btc, eth, sol). This gives the agent actionable meaning 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 states a specific resource and action: current perpetual funding rates across six named exchanges, or historical rates for a symbol by slug. It clearly identifies what the tool returns and is distinct from the other financial data siblings.

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 implies usage modes: omit slug for current rates, provide a slug for history. However, it does not explicitly state when to prefer this over sibling tools like crypto_market, nor does it mention exclusions or prerequisites.

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