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

Adds context beyond the annotations: rates are gross/before costs, results are pre-sorted (highest first, or by absolute APR), and the OI filter is a top-N-only constraint. This is meaningful interpretive guidance for a read-only tool whose annotations already cover safety.

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?

Three tight sentences, front-loaded with what the tool returns followed by the two mode behaviors. The telegraphic 'With/Without' phrasing is dense but wastes nothing.

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?

With no output schema, the description should say more about what comes back – units of the rate (APR vs per-interval), fields per market, or ordering ties. It covers mode behavior and the gross/before-costs caveat, but leaves the return shape underspecified.

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 coverage is 67% with `limit` undocumented; the description compensates by explaining that `base` expands to all exchanges for one coin and that `limit` means N in the top-N mode, and reinforces that `min_oi_usd` only applies without `base`. It doesn't state the sort key units, but adds real meaning over 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?

States a specific resource (current perpetual funding rates) and distinguishes its two operating modes by the presence of `base`. An agent can tell this apart from siblings like borrow_rates or basis_trades, though no sibling is named explicitly.

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?

Gives clear conditional guidance: pass `base` to get one coin across every exchange sorted by rate, omit it to get the top N markets by absolute APR with an OI filter. It lacks explicit exclusions pointing at alternative tools, but the mode-selection rules are unambiguous.

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