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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, and the description reinforces this without contradicting it ('Reads or computes only and changes nothing'). It adds behavior the annotations cannot express: majors are filtered by default, symbolClash flags copied symbols so results must be matched by address, and every call is billed ($0.01 via x402/card, first 25 free, failed calls free, repeats not free).

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?

Dense but front-loaded: purpose, data sources, exclusions, then caveats and pricing. Every sentence carries information, though the pricing/payment clause is long and sits mid-paragraph where it competes with the usage guidance for attention.

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 usefully enumerates the return fields (swaps, pools, share of swaps, symbol, name, busiest pool) and explains the symbolClash field, which an agent could not otherwise interpret. Remaining gaps are minor: result ordering, behavior on thin/empty windows, and whether the per-call charge applies to rate-limited or retried calls.

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 100%, so baseline is 3, but the description adds real meaning: it frames 'blocks' as a live lookback window over swap events ('default 5, up to 10' minutes, matching the 30-300 block range) and clarifies that the majors filter defaults to exclusion 'unless asked'. It stops short of explaining how 'limit' interacts with ranking or tie-breaking.

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 names a specific resource and scope ('Trending tokens on Base now') and defines it operationally: tokens with the most DEX swaps counted live from Uniswap v2/v3, Aerodrome and Slipstream events. It also separates itself from siblings by pointing at token_report for the follow-up check, so an agent can choose between them without reading either schema.

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?

It states the intended use ('spot what traders buy now'), the required follow-up ('check token_report before trading'), and a default the caller may not expect (majors left out unless asked). It even gives a worked invocation ('blocks=150'), which is unusually explicit routing guidance.

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