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

No annotations are provided, so the description carries the full burden for behavioral disclosure. 'Fetch' implies a read-only operation, but the description does not explicitly state that, nor does it describe the return format, error handling, or authentication requirements. It does disclose the significant nuance that for-sale and for-borrow copies have different IDs/SKUs, which adds useful behavioral context, but other operational details are missing.

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 concise at two sentences with no filler. The first sentence front-loads the main action and object, and the second sentence adds essential usage constraints and the borrow-copy caveat. Every clause earns its place; it is neither under-specified nor verbose.

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 no output schema or annotations, the description is the only source of contextual info. It clarifies the identifier selection and the sale/borrow nuance, which is strong. However, it does not describe what 'full details' includes (e.g., fields returned), and it does not address edge cases like supplying both id and sku. For a simple, single-resource tool, this is adequate but not complete; an agent might not know the exact shape of the response.

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 already describes both parameters fully (100% coverage), so the baseline is 3. However, the description adds valuable meaning beyond the schema: it explicitly states the mutual exclusivity of 'id' and 'sku', and it explains the SKU suffix '-L' for borrow copies, which is essential for correct input selection but absent from the raw schema. This elevates the parameter semantics.

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 ('Fetch') and a clear resource ('full details for a single book'), and it uniquely identifies the tool by requiring either a numeric ID or an exact SKU. It implicitly distinguishes itself from the sibling 'search_books' by focusing on a single book known by identifier, rather than a search across multiple results.

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 provides clear conditions for usage: you must know the exact numeric ID or SKU, and it explicitly states to provide exactly one of them. It notes the sale-vs-borrow distinction, which is crucial for selecting the correct identifier. However, it does not explicitly mention when to choose this tool over 'search_books' (e.g., when an exact ID/SKU is known), so the guidance is clear but not fully explicit about alternatives.

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

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

With no annotations provided, the description takes on the full responsibility for behavioral disclosure. It discloses a key quirk: the same book can appear as two different rows (for-sale vs. borrow) with different SKU patterns, and it explains the meaning of the 'availability' field. This adds meaningful context beyond the schema, though it does not mention other behaviors like rate limits or permission requirements. The disclosure of the duplication and availability semantics is substantive, earning a 4.

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 concise and front-loaded: the core action and keys appear in the first sentence, followed by a needed clarification. There is no fluff or repetition; every sentence—the search scope, the duplicate-entry insight, and the availability field explanation—adds necessary context. Overall, a well-structured, efficient description.

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?

The description covers the non‑obvious facets of the tool: the possible duplicate rows and the meaning of the 'availability' field. The schema documents all parameters, and the sibling-tools context implies a separation from get_book. While some details like error behavior or whether results are ordered is missing, the description is sufficient for the typical use case. A 4 reflects that it handles the main specifics and leaves only minor edge dimensions unaddressed.

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%, so the baseline is 3. The description does not add significant new meaning to the parameters themselves—the mention of title/author/ISBN already appears in the `query` description, and the `availability` param is already explained. The added value is mostly about result interpretation rather than parameter semantics, so a 3 is appropriate.

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 clearly states the tool’s purpose: searching kvartirabooks.org's catalog by title, author, or ISBN/SKU. It also explains the important nuance that a single book can have both for-sale and borrow copies, which clarifies exactly what the tool returns. This unambiguous verb (search) + resource (catalog) + search keys makes it easy to distinguish from the sibling tool get_book without confusion.

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 establishes when to use this tool (when there is a search query for title, author, or ISBN/SKU) and the nature of the results, but it does not explicitly discuss when to prefer the sibling get_book (e.g., when a specific book ID is known) or any exclusion conditions. This is a minor gap given that the search vs. fetch distinction is fairly obvious, so clear context with no exclusions merits a 4.

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