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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false and openWorldHint=true, so the mutation profile is covered. The description adds one genuinely useful behavioral insight — that the description text is what the AI uses at runtime to decide whether to send the image — but says nothing about duplicate handling, permissions, or side effects it does not mention.

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 sentences, front-loaded with the purpose and followed by the key guidance for the critical parameter. Nothing is wasted, though the second sentence is a slightly dense run-on rather than crisply structured.

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?

No output schema is needed here, the schema fully covers parameters, and annotations carry the safety/mutation profile, so the description only needs to convey purpose and the semantics of the key field — which it does. Minor gaps remain around idempotency and website targeting behavior.

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 schema already documents all three parameters, giving a baseline of 3. The description reinforces the meaning of the required "description" field ("describe what it shows and when it helps"), but adds only marginal detail beyond the schema's own wording.

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 and resource ("Add an image the chatbot may show"), making it clear this registers an image asset for the chatbot to surface. It does not differentiate itself from close siblings like add_knowledge_text or add_knowledge_url, so it stops 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?

Usage context is only implied: the second sentence explains that the AI reads the description to decide when the image answers a question, which hints at the image-serving use case. There is no explicit when-to-use-this-vs-alternatives guidance or routing to add_knowledge_text/add_knowledge_url.

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