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

Annotations already establish read-only, idempotent, and non-destructive behavior. The description goes beyond annotations by disclosing the measurement basis ('base fee tier'), the temporal scope ('newest stored 6-hour sweep'), and the handling of unconfirmable rows ('Rows that cannot fill or have unconfirmed depth are listed apart, with the reason'). This adds meaningful transparency about output structure and edge cases, without contradicting annotations.

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 two sentences, front-loads the core purpose and metric, and wastes no words. It packs essential context (data source, edge-case handling) into a compact form, making it highly efficient for an agent to parse.

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?

There is no output schema, but the description conveys that the result is a ranked list of venues separated by fill-ability status, which implies the output structure. It does not mention pagination, result count, or whether costs are shown as numbers, but for a simple ranking tool this is sufficient. The absence of an output schema places more burden on the description to hint at returns, which it does adequately.

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% and both parameters (asset, size) have descriptive enums and inline descriptions. The tool description does not add any parameter-specific meaning beyond the schema; it focuses on the tool's overall behavior. Given the high schema coverage, a baseline score of 3 is appropriate.

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 verb ('ranked'), resource ('venues'), and precisely defines the ranking metric ('measured all-in cost (taker fee + half-spread + price impact) of a perp market buy'). It also clarifies the data source ('newest stored 6-hour order-book sweep') and the handling of invalid rows, which clearly differentiates it from siblings like get_venue_fees (fees only), get_funding (funding), and get_volume_ranking (volume).

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 for comparing venue costs on a perp market order, and the cost components are explicit. However, it does not explicitly state when not to use it or name alternative tools, though the sibling tools are clearly different in scope. The context is clear enough that an agent can infer appropriate usage, but it stops short of explicit disambiguation.

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