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

Annotations only declare readOnlyHint and openWorldHint=false; the description adds substantial context beyond them: data provenance (in-person photos of tags and receipts), geographic scope (Hamburg and suburbs), aggregation behavior (14-day medians, change vs earlier observations), and the shape of the response (latest price with store and district, basket total, recent entries). With no output schema, this return-content disclosure is exactly what carries the load.

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?

Front-loaded with the resource and scope, and every sentence adds retrieval-relevant information. The long inline product list (milk, butter, eggs, ... Iglo Schlemmerfilet 380 g) is somewhat sprawling, but it earns its place by giving an agent concrete match terms.

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?

No parameters, no output schema, and a simple read-only operation — the description supplies provenance, coverage, aggregation window, and return contents, which is everything needed to call it correctly and interpret results. Nothing material 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?

Zero parameters, so the baseline is 4; there is nothing parameter-wise for the description to clarify or omit. The description's itemized coverage list compensates indirectly by telling the agent what the unfiltered result will contain.

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+resource: real shelf/pump prices from Hamburg shops, read from photos of price tags and receipts. It enumerates covered categories and explicitly distinguishes itself from promo flyers and official fuel price feeds, so an agent knows exactly what dataset it is querying.

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?

Ends with an explicit routing sentence: 'Use it for questions about the cost of living, groceries or fuel in Hamburg.' It also implicitly excludes promo-flyer and official fuel-feed use cases by contrast. No sibling tool overlaps (the siblings are unrelated radar/track/vote tools), so no alternative routing is required, but there is no statement of what it cannot answer (e.g., stores outside Hamburg, historical series beyond the 14-day window).

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