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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, indicating a safe read operation. The description adds that it returns 'rate, period, last funding timestamp' and notes that period is informational (1h/8h/24h), providing beyond-annotation context. However, it doesn't clarify if period affects the data returned or is just a filter.

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?

Description is concise with two sentences: first states the core purpose, second adds examples and clarification. No unnecessary words. Could be slightly more structured (e.g., bullet points) but is very efficient and easily readable.

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?

Given the presence of an output schema and annotations, the description provides reasonable context: it explains the key input (market) and output shape (rate, period, timestamp). However, it omits purpose of caller_id and doesn't clarify period's effect on results. Complete enough for a simple read-only tool but has minor gaps.

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 0%, so the description must compensate. It provides meaning for market (example SOL-PERP) and period (informational with allowed values), but caller_id is not mentioned. This partially covers the parameters but misses one, making it adequate but not thorough.

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?

Description clearly states it returns current funding for a perp market, including rate, period, and last funding timestamp. It gives an example market (SOL-PERP) and mentions period options. However, it does not explicitly distinguish from the sibling tool 'perp_funding_rates_all', which likely returns data for all markets, missing an opportunity for differentiation.

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?

No explicit guidance on when to use this tool over alternatives like perp_funding_rates_all or perp_markets. While it implies usage for a single market via example, it does not state when to choose this tool vs. others, leaving the agent to infer.

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