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

Annotations already declare readOnly, idempotent, non-destructive, and open-world, so "no side effects" is largely redundant. The description does add value annotations do not carry: no authentication is required, and the returned series is a bounded ~180-day daily window. It stops short of noting rate limits or whether very old data is truncated.

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 short sentences, front-loaded with the core purpose, then the constraint, then the alternative. Every sentence carries distinct information with no filler.

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?

An output schema exists, so return values need not be described. Between the description (scope, auth, mutual-exclusivity, alternative routing) and the annotations (safety profile), an agent has everything required to call this 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 coverage is 100%, so baseline would be 3, but the description adds the mutual-exclusivity rule ("Pass exactly one of itemId or name") that the schema's additionalProperties:false does not actually express. Neither parameter is declared required in the schema, so this constraint is genuinely additive.

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?

States a specific verb and resource ("Read ... daily price series for one item") plus the scope ("about the last 180 days"), which is far more precise than the bare title. It is readily distinguishable from siblings like get_item_price (current price) and summarize_price_history (aggregates).

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?

Explicitly routes the agent away from this tool when aggregates are wanted: "Use summarize_price_history for min, max, and average instead of the raw series." However, it does not clarify how it differs from the closer siblings get_item_price and lookup_item, so guidance is clear but incomplete.

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