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

Annotations already provide readOnlyHint and openWorldHint, so the safety profile is clear. The description adds meaningful behavioral context beyond annotations: it explains the data is historical delivery/settlement price at expiry, that it is quarterly-only, and that perpetual pairs are out of scope. It does not describe response structure, but the schema's detail parameter partially covers that.

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 with no filler. It front-loads the core purpose, then adds the critical scope restriction and pair-format instruction. Every phrase earns its place.

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 two-parameter read-only tool with detailed schema descriptions and annotations, the description adequately covers what, when, and how. It explains the quarterly-specific nature and pair selection. It does not describe exact response fields or date-range behavior, but given the schema's detail enum and the tool's simplicity, the overall context is sufficient.

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 schema already explains both parameters thoroughly. The description reinforces the pair format rule ('TANPA suffix margin-asset') and clarifies quarterly relevance, but does not add substantive new meaning beyond what the schema already provides. A baseline 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 clearly states the tool retrieves historical delivery/settlement prices for quarterly contracts, specifically the final price at contract expiry. It explicitly distinguishes the tool from perpetual-related tools by stating it does NOT apply to PERPETUAL contracts, and clarifies the correct pair format.

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 gives clear context on when to use this tool: only for quarterly/dated listing pairs, and explicitly warns against using it for PERPETUAL contracts. It also instructs to use the pair without the margin-asset suffix. However, it does not name alternative sibling tools for when one should not use this tool, so it falls just short of the highest guidance level.

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