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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds value beyond these by clarifying that the tool returns only availability and town name, and by reinforcing that it is non-mutating and privacy-limited. No contradictions with annotations.

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 three tightly scoped sentences with no redundant phrasing. The main purpose is front-loaded, followed by output scope and then explicit non-behaviors, making it easy for an agent to parse quickly.

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 simple one-parameter, read-only lookup with no output schema, the description is complete: it explains the input format, what the response will contain (availability and town name), and what it will not do. Combined with the annotations, an agent has everything needed to invoke it correctly.

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?

With 0% schema description coverage, the description carries the burden for explaining the postal_code parameter. It specifies the format (NN-NNN, e.g. 83-300), which is essential, though it doesn't mention that the hyphen is optional as the schema allows. This is a minor gap but still provides meaningful guidance beyond the raw pattern.

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 starts with a specific verb ('Checks whether SzuruSzuru serves a Polish postal code') and a precise resource (postal code), and distinguishes itself from booking/scheduling siblings by explicitly stating it does not reserve anything and does not reveal staff or schedules. This makes the tool's unique role immediately clear.

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 clearly implies when to use the tool: to verify service coverage for a postal code before booking. It provides exclusions ('Does not reserve anything and does not reveal staff or schedules') that prevent misuse, though it does not explicitly name an alternative sibling such as check_availability.

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