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

The annotations already establish readOnlyHint=true and openWorldHint=false, so safety and locality are covered. The description adds valuable provenance ("eigen metingen van NuActueel, met links") and discloses the data sources per field (bol, Open Icecat, Coolblue, Teufel), but it does not address what happens with mismatched product types, missing data, or whether the two products must share a category.

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 tool's purpose is front-loaded in the opening clause, with the returned data listed afterwards. The parenthetical examples and quoted advice fragment add concrete value, though the single long sentence packs several clause levels and could be broken up for easier scanning.

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 two-parameter read-only comparison tool with no output schema, the description covers purpose, input expectation (same kind of product, name or EAN), data sources and return contents, plus provenance. Nothing an agent needs to invoke it correctly 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?

Schema description coverage is 100%, and both parameters are documented as name or EAN, so the schema already does the heavy lifting. The description reinforces the constraint that both products must be of the same kind, which adds a little meaning beyond the schema, but offers no detail on name formatting, disambiguation, or which product is treated as the reference.

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 states a specific verb and resource: putting two products of the same kind side by side, and it enumerates what the comparison returns (current prices at Coolblue/bol/Teufel, buying-advice, differing and identical specs). This clearly distinguishes it from siblings like product_info or product_prijs, though it never names those siblings 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?

The description gives clear usage context: two products of the same type (with concrete examples like "Galaxy A57" vs "Galaxy A56", or two TVs), and it implies the output is comparison-oriented. It does not state exclusions or explicitly route to alternatives such as product_prijs for a single price, so it falls short of a full when/when-not treatment.

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