Find a Reknihy book by ISBN

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and non-destructive behavior, so the safety profile is covered. The description adds useful scope context ('public catalog') and exact-match semantics, but does not disclose behavior like no-match results or return format. This is acceptable given the strong annotation coverage.

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?

One sentence, front-loaded with the operation and scope, with zero filler. Every phrase contributes meaning, and the description is immediately scannable.

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 one-parameter, read-only, idempotent lookup with a clear resource and sibling context, the description is sufficient. It omits what happens when no match is found, but the operation is simple enough that this is a minor gap rather than a blocking one.

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?

The schema provides 100% parameter coverage for the single isbn parameter, including hyphen flexibility. The description adds the ISBN-10/ISBN-13 format constraint and reinforces the exact-match intent, which is a small but genuine semantic increment beyond 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 uses a specific verb ('Find'), a precise resource ('public Reknihy.cz catalog'), and an explicit qualifier ('exact ISBN-10 or ISBN-13 match') that distinguishes it from a broader search. An agent can immediately tell this tool is for precise ISBN lookup rather than fuzzy queries.

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 phrase 'exact ISBN-10 or ISBN-13 match' gives a clear trigger condition: use this when a precise ISBN is known. It does not explicitly name alternatives like search_books for partial matches, but the exact-match language provides clear context without needing an exclusion list.

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