get_film_image

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

Annotations only declare readOnlyHint and openWorldHint, but the description adds real behavior: it checks the thumbnail first and plainly reports whether the image exists, so bad numbers yield a clear answer rather than a failing URL. It also discloses the auth requirement — thumbnail is readable without a token, the full page needs one.

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?

Purpose is front-loaded in the first sentence and every remaining sentence adds routing or behavioral value. It is a bit loose and multi-line, but no sentence is filler.

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, the description carries the return burden and does explain the existence-check behavior and token distinction. It stops short of detailing exact return contents, but for a read-only image locator it is nearly complete.

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 100% with good per-field descriptions, so the baseline is 3. The description adds provenance value by naming the source fields (FS_DIGITAL_FILM_NBR, FS_IMAGE_NBR) on indexed records, helping the agent know where to obtain the values.

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+resource ('Reach a page image') and a distinctive access path ('by film and image number instead of by ark'). It explicitly distinguishes itself from the siblings get_image_links and get_record_image, so an agent can disambiguate without opening any schema.

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 when to use it (citations name film+image, not an ark) and names the alternatives it is not: get_record_image reports the numbers, and get_image_links cannot help because there is no ark. This is explicit when/when-not/alternatives coverage.

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