Find images without alt text on a web page

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

Annotations declare readOnly=false and openWorld=true, so the description rightly adds the cost/behavior model (free default, 1 credit per image when generate is on) and clarifies that an empty alt attribute is correct for decorative images, which prevents false-positive reporting. It does not cover failure modes for non-public URLs, but it meaningfully supplements 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?

Three tight sentences with the core capability and the missing/empty distinction front-loaded, followed by the cost model. Every sentence carries information; nothing is repeated or padded.

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-value burden and does so by naming the two result categories and their meaning. It stops short of describing the per-image output shape or what happens when a page cannot be fetched, leaving a small gap for a 4-parameter, open-world 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%, so 'url', 'generate' (including its 1-credit cost), 'language', and 'max_images' are already fully documented. The description restates the generate/credit semantics but adds nothing about language or max_images, so the baseline 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?

States a specific verb and resource ('Reads a public web page and lists the images that have no alt attribute'), and further disambiguates the two result buckets (missing vs empty). It does not name any sibling tool, so the distinction from generate_alt_text depends on the agent inferring it from the audit framing, which keeps it short of a 5.

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?

Gives clear operating context: free by default, and 'Set generate to true to also write suggested alt text for the images found, which uses 1 credit per image' tells the agent exactly when the paid path activates. No explicit when-not-to-use or named alternatives (e.g. vs generate_alt_text), so no 5.

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