Generate alt text from a local image file

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

Annotations cover the safety profile (writes state, open world, non-idempotent), and the description adds genuinely useful context beyond them: the accepted formats, the 3 MB size ceiling, and that the call consumes 1 credit from the AltTextGeneratorAI account. It does not say what the response contains, but the cost and input constraints are real value-adds.

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 tightly written sentences with zero filler, front-loading the action and resource before the operational constraints and cost.

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?

For a two-parameter tool with no output schema, the description covers purpose, accepted inputs, and the credit cost, which is enough to invoke correctly. An agent would still benefit from knowing the return shape (whether the alt text comes back inline) and that repeated calls are billed separately.

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%, so the baseline is 3; the description goes further by imposing constraints on file_path (JPEG/PNG/GIF/WebP, max 3 MB) that appear nowhere in the schema. The language parameter is left to the schema, which already explains defaults and the 130+ language support.

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 (writes) and resource (SEO-friendly, accessible alt text) scoped to a local image file, with format and size limits. The local-file scope implicitly distinguishes it from the sibling generate_alt_text, but the difference is never stated outright.

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?

Usage is implied rather than stated: 'an image file on this computer' tells the agent this is the local-file path, and the mention of credits hints at a budget concern. There is no explicit when-to-use or when-not rule, and no named alternative (e.g. generate_alt_text for non-local sources).

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