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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the basic safety profile. The description adds extra behavioral context: 'Read-only public research data. No account access, no order placement or fund transfers. Not investment advice.' This reinforces that no side effects occur and clarifies the data scope. The description also clarifies a data-specific behavior (CEX perps via exchange_slug) that isn't captured in annotations. It doesn't add details on return format or pagination, but the output schema exists. Hence a 4 is appropriate.

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 description is concise, with each sentence earning its place. It front-loads the core purpose, then provides routing alternatives, then a specific usage case, then safety disclaimers. No fluff or redundancy. The information density is high without being unwieldy.

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 read-only time series tool with a full output schema, the description covers all essential aspects: it names the exact data (TVL, volume, fees), clarifies the single-protocol scope, routes to sibling tools, explains CEX perps handling, and declares safety limitations. The output schema handles return value explanation, so no further detail is needed. The description is fully sufficient for an agent to decide when to call it and how.

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. The description adds value by clarifying the interplay between exchange_slug and platform_name: 'CEX perps history: pass exchange_slug (e.g. gate) or platform_name.' This explains when to use which parameter, which is not fully evident from the schema alone. It also mentions the metrics parameter's default in a prior sentence ('Daily TVL, volume, and fees'), which helps understand the metric options. This extra guidance justifies a 4.

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 clearly states the tool returns 'Daily TVL, volume, and fees time series for one named protocol,' specifying the exact resource (one protocol) and data type. It also distinguishes itself from siblings by naming them: 'One-shot profile→get_platform_info. Ranked multi-protocol list→search_platforms.' This disambiguation is explicit and leaves no ambiguity about scope.

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 provides direct routing guidance: for a single protocol profile, use get_platform_info; for a ranked multi-protocol list, use search_platforms. It also gives a specific conditional usage: 'CEX perps history: pass exchange_slug (e.g. gate) or platform_name.' This goes beyond general usage and covers edge cases, making the when-to-use crystal clear.

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