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

Annotations already establish readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuine interpretive context by disclosing the data source (marketplace listings) and the aggregation method (rolling, fine-metal-weighted median of asking prices), but says nothing about pagination via the cursor, data freshness, or rate limits.

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?

A single dense sentence with no filler, front-loading the metric definition. It is slightly list-heavy at the tail, but every clause (weighting, median, source) carries interpretive value.

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?

With an output schema present, return values need no explanation, and annotations cover the safety profile; the methodology sentence completes the picture of what the numbers mean. The main gap is pagination/continuation behavior implied only by the cursor parameter.

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 every parameter (metal enum, query, limit, cursor) is documented in the schema itself, so the baseline is 3. The description adds no additional parameter meaning beyond listing the metal values, which the enum already provides.

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 names a specific resource (rolling fine-metal-weighted median asking premiums) and enumerates the covered metals, so an agent can distinguish it from get_spot_prices and get_price_history. It is clear about what is returned, though the verb is only implied by the tool name rather than stated.

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?

There is no when-to-use guidance: nothing says to call this instead of get_spot_prices when the agent needs a markup over spot, nor any mention of prerequisites or the relationship to the spot-price tools. Usage must be inferred entirely from the name and the word 'premiums'.

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