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

With no annotations, the description carries the full behavioral burden. It usefully discloses that results are deduped and resolved to absolute URLs and that it is a paid operation sharing run_query's price and payment flow, but it defers the actual payment/auth mechanics to a sibling rather than explaining them and says nothing about failure modes or rate limits.

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?

A single front-loaded sentence with an em-dash that first states the purpose, then the return shape, then the pricing caveat. Every clause earns its place and nothing is redundant.

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?

There is no output schema, yet the description explains the return values (image sources as absolute URLs with alt text, deduped), which covers the main gap. Payment and auth details are handed off to run_query rather than restated, leaving a minor completeness shortfall for a paid 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 only 33%: url is documented in the schema, but agentId and paymentHeader are undocumented in both schema and description. The mention of 'payment flow' loosely signals that a payment parameter is required, but agentId receives no clarification, so compensation for the coverage gap is partial.

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?

It states a specific verb and resource ('fetches a URL and returns every image source... with alt text, deduped') and explicitly positions itself relative to a sibling by calling out it is a wrapper around run_query with mode="images". An agent can distinguish it from extract_links and run_query 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?

It names the alternative (run_query with mode="images") and clarifies this is a convenience path, giving clear context for when to reach for it. It lacks an explicit exclusion such as 'do not use for links, use extract_links' or a condition list, so it falls short of full routing guidance.

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