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

Annotations already mark readOnlyHint=true and destructiveHint=false, revealing it as a safe read operation. The description adds valuable context: suspended periods are deliberately withheld and counted, fully-suspended spans fail with a reason, and it discloses free/CC BY 4.0 licensing and no API key requirement. This goes beyond annotations, though it does not cover pagination or rate limits, which are not critical given the read-only nature.

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 sentences, each purposeful: the first states the action and data scope, the second clarifies edge-case behavior, and the third covers licensing and authentication. Front-loaded with the core functionality, no redundancy or fluff. Efficient and well-structured.

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?

The tool has an output schema, so return format is presumably covered elsewhere. The description covers the data types, special handling of suspended periods, licensing, and auth. The only notable gap is the 'series' parameter—what a valid series identifier looks like—but this is a minor omission for a data-fetch tool with moderate complexity. Overall, the agent has enough to call it correctly.

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 75% (three of four parameters have descriptions: 'Inclusive end', 'Inclusive start, YYYY-MM-DD or YYYY-MM', 'Max rows, default 2000'). The description adds no additional meaning to parameters; it only states the general purpose. Since schema coverage is high, baseline 3 is appropriate, but the 'series' parameter remains undescribed both in schema and description, so no value is added beyond 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?

The description states a specific verb ('Fetch') and a precise resource: 'data of a series' with enumerated content types (monthly US port trade, tariff rates, collected duty) and format ('as periods and values'). This strongly distinguishes it from siblings like tariff_lookup or trade_query by clarifying it returns time-series data. No ambiguity about what the tool does.

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?

No guidance on when to use this tool versus alternatives. It does not mention conditions like 'use for time-series queries' or name any sibling tools. The description implies a series-based use case but offers no explicit routing or exclusions. Agents have to infer when to select this over trade_query or tariff_story.

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