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

Annotations only declare readOnlyHint and openWorldHint; the description goes further by disclosing the source fallback order, the ranking rule (title/tag matches first), the requirement to pass a bare word plus language, and what each result carries (image_url and credit). It stops short of rate limits, latency, or failure behavior, but adds substantial context beyond 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?

Front-loaded with the resource and source chain, with the parameter instruction and return-shape note trailing. The middle sentence is a long run-on but every clause (source order, sort rule) earns its place; only minor tightening is possible.

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 compensates by naming the returned fields (image_url, credit) and their intended use. It also covers input conventions and the multi-source ranking, leaving little ambiguity for a correct invocation, though it omits fallback behavior when fewer sources match.

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, but the description adds real meaning: the concrete example that "hus" in nb finds a house clarifies language-dependent lookup, and it cross-references list_languages for valid codes. That is more than the schema's own field descriptions provide.

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 (find openly licensed pictures for a word) and even enumerates the source chain — Wikimedia Commons, Pixabay, Openverse. It is trivially distinguishable from the deck/design siblings, none of which retrieve images.

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 through the hint that each result has an image_url to put on a card, but there is no explicit when-to-use vs. alternative, no exclusion, and no mention of how it relates to siblings like create_design. The instruction to pass the bare word and its language is helpful but is parameter guidance rather than tool selection guidance.

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