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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds real behavior beyond that by disclosing the output shape (min/max/avg grouped by kind:unit) and the scope (all live offers, no filtering) — valuable given there is no output schema — but says nothing about data freshness, caching, or how units are normalized.

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 single sentence front-loads the core concept and the aggregation detail, with no redundant restatement of the title. The trailing "nobody else normalizes compute+storage+bandwidth+inference together" is promotional filler that does not help an agent decide or invoke.

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 zero-parameter, read-only aggregate with no output schema, the description covers what is computed, the grouping key, and the population being aggregated. Freshness or the exact response envelope would be the remaining gap, but nothing essential for a correct invocation is missing.

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?

The tool takes zero parameters and the empty schema is fully described, so there is nothing for the description to disambiguate. Baseline 4 applies; the description correctly signals that the call is unfiltered and global.

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 uses a concrete verb-and-resource framing ("Cross-resource price index") and spells out exactly what is computed: min/max/avg provider price per kind:unit across all live offers. It is clearly an aggregate over offers rather than a listing, which separates it in spirit from wide_offers, though it never names that sibling explicitly.

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?

Usage is only implied: an agent can infer this is the tool for aggregate price comparison rather than per-offer lookup, and the claim about normalizing compute+storage+bandwidth+inference hints at when it beats narrower stats tools. There is no explicit when-to-use/when-not statement and no named alternative such as wide_offers or feed_stats.

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