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

Annotations already establish readOnly and non-destructive behavior. The description adds useful behavioral context: the result is a directly embeddable image URL, the logo is selected for the named background, and only one asset is returned rather than a full record. This goes beyond the annotation baseline without contradicting it.

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 with no filler. The first sentence states the core value and output form; the second delivers the usage decision and cost/benefit comparison. Every clause earns its place.

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 simple read-only tool with fully documented parameters and helpful annotations, the description covers what an agent needs: the output type, the background-dependent behavior, and the distinction from the closely related sibling. The absence of an output schema is acceptable because the description names the return format directly.

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. The description adds modest contextual meaning by mentioning 'background you name' (echoing theme) and 'mark' (echoing icon vs full logotype), but it does not materially expand parameter understanding beyond the schema.

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 clearly identifies the tool's output as a company logo image URL and ties it to a background choice. It also explicitly contrasts with the sibling brand tool ('Use this rather than brand'), so an agent can distinguish it without inspecting schemas.

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?

The description gives explicit selection guidance: use it instead of brand when only the mark is needed, and cites concrete benefits (lower cost, single asset returned). This is actionable and names the alternative directly.

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