Compare 2-5 deals side by side (price, unit, offer type, code, verification), best value first.
| Name | Required | Description | Default |
|---|---|---|---|
| ids | Yes | ||
| mode | No | full |
| Name | Required | Description | Default |
|---|---|---|---|
| ok | Yes | ||
| mode | No | ||
| deals | No | ||
| error | No |
Changes observed during successful MCP inspections.
Output schema / properties / error / properties / code / enumPrevious value: -[
- "invalid_argument",
- "invalid_cursor",
- "not_found",
- "feed_unavailable",
- "feed_invalid",
- "upstream_unavailable",
- "internal_error"
-]New value: +[
+ "invalid_argument",
+ "invalid_cursor",
+ "cursor_expired",
+ "not_found",
+ "feed_unavailable",
+ "feed_invalid",
+ "upstream_unavailable",
+ "internal_error"
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real behavioral value by stating results are ordered 'best value first', but leaves the ranking criterion ('best value') undefined, which is the key behavioral unknown for interpreting output.
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 front-loaded sentence with zero filler: verb, scope, compared fields, and result ordering all in one line. Nothing is wasted.
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 structure need not be explained. But for a 2-parameter tool with 0% schema coverage, the unexplained 'mode' parameter and the unspecified ids delimiter leave genuine gaps an agent would hit on first invocation.
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 0%, so the description carries the full burden. It hints that 'ids' holds multiple deals (2-5) but never gives the format (comma-separated? array in a string?), and the 'mode' parameter (default 'full') is entirely undocumented in both schema and description.
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 (compare) and resource (deals) with scope (2-5) and the compared attributes (price, unit, offer type, code, verification). It implicitly distinguishes itself from get_deal (single) and compare_gpu_prices (domain-specific) but never names those siblings, so an agent must infer the boundary.
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 '2-5 deals' range implies this is for multi-deal evaluation rather than single lookups, which is useful implied guidance. However, it never states when to prefer get_deal, search_deals, or compare_gpu_prices instead, and gives no precondition that ids must reference existing deals.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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