Read an item

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

Annotations already declare readOnly/idempotent/openWorld, so the bar is lower; the description still adds real context: file lists on scanned items 'run to dozens of derivatives', 'full_metadata' is large and rarely needed, and file_count/total_bytes are always returned regardless of sections. That response-shape and size information is not derivable from the 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?

Front-loaded with the verb and identifier source, then walks through sections in a single dense paragraph with no filler. Every clause conveys operational information about cost or filtering.

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, the description needn't document return values, yet it still tells the agent which response components are always present. Combined with section cost guidance, an agent has everything needed to call this correctly on the first attempt.

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 coverage is 80%, so a baseline of 3 applies; the description goes beyond it by explaining what each section actually contains and why 'files' can be expensive, plus the fact that file_count and total_bytes are unconditional. The max_description_chars parameter is left unexplained in the description, which the schema itself also omits.

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 and resource — 'Read one Internet Archive item by its identifier' — and distinguishes itself from the sibling search tools by naming where the identifier comes from. An agent can tell this is a single-record fetch, not a search.

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?

Explicitly says the identifier comes from search_items or search_inside, and gives per-section guidance on when to ask for 'files' (filter by format when a particular derivative is wanted) or avoid 'full_metadata' (large, rarely needed). It does not address when to prefer get_snapshot or how this relates to search_books, but the core usage framing is strong.

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