lookup_isbn

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

No annotations are provided, so the description carries the behavioral burden. It does disclose it aggregates from multiple providers and specifies which fields are returned 'when available,' implying possible missing data. However, it doesn't clarify data freshness, potential ISBN format normalization, or what happens for unknown ISBNs.

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?

Two sentences, front-loaded with the primary purpose in the first sentence and return fields in the second. Zero wasted words. Slightly low on structural formatting (no breaks) but appropriately tight for the content.

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?

With an output schema present and a single well-documented parameter, the description doesn't need to explain return types. The aggregation provider list and field enumeration provide useful context. A small gap is not framing the 'when available' caveat more explicitly, but overall this is reasonably complete for a simple lookup tool.

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% with the isbn parameter well-documented (ISBN-10 or ISBN-13, with or without hyphens). The description adds context about what the lookup returns but doesn't add parameter-level semantics beyond what the schema already covers, which is the baseline-3 scenario.

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+resource ('look up a book's metadata by ISBN') and lists the exact fields returned (title, authors, publisher, year, synopsis, dimensions). It clearly distinguishes from siblings like lookup_cnpj and lookup_cep which target different entity types.

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 implicitly conveys use for looking up book metadata and names the aggregated provider sources (CBL, Mercado Editorial, Google Books), but provides no explicit when/when-not guidance or alternatives. For a lookup tool with clearly distinct siblings by entity type, this is adequate but not exemplary.

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