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

The description provides extensive behavioral context beyond the readOnlyHint annotation: it warns not to fetch or click product_url, explains the commissionable session trigger, and details what full=true returns. It also clarifies intent_match_only semantics. This adds significant value beyond the annotation's simple read-only declaration.

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 description is somewhat long but every sentence delivers necessary information about URL handling, projections, and special flags. It is front-loaded with the core purpose and then layers details logically. While dense, it is not verbose or redundant, earning a solid score just below maximum.

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?

Given the absence of an output schema, the description effectively explains the return structure for both compact and full modes, including the key fields. It covers the crucial safety and behavioral aspects of product_url handling. The only minor gap is the undocumented intent_match_only parameter, which could leave an agent uncertain about its validity, but the description is otherwise comprehensive.

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% for the listed parameters (full and deal_id). The description adds meaningful semantics by explaining the default projection, what full=true returns (specs, SKU, price history, etc.), and introduces intent_match_only (which appears only in the description, not the schema). This adds value, though the intent_match_only mention could cause confusion due to its absence from 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 clearly states 'Fetch one deal by id' with a specific verb and resource, distinguishing it from sibling tools like search_deals or latest_deals. It also specifies the scope (one deal) and provides detail on default vs full projections, leaving 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?

The description gives clear usage guidance on when to use full=true versus the default compact projection, and explicitly states to use product_url_canonical for automated needs instead of product_url. However, it does not explicitly name alternative sibling tools or state when not to use this tool, though it is implied that this is for fetching a single deal by ID.

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