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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), so the bar is lower. The description adds two useful facts beyond them: results are sourced from the company's own site and multiple alternatives are returned. It stops short of describing the return shape (single URL vs. ranked list) or failure behavior when no logo exists.

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 sentence with the core value ('best logo/icon URL for a domain') front-loaded and no wasted clauses. Slightly dense due to the stacked qualifiers, but appropriately sized for a one-parameter lookup tool.

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 one-parameter tool with no output schema and full annotation coverage, the description is close to adequate. The gap is the return contract: it says 'with alternatives' but never explains whether that means multiple URLs, a ranked list, or a fallback chain.

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% and the single parameter carries an example ('e.g. stripe.com'), so the schema does the heavy lifting. The description adds only the implied notion that a domain identifies the company, which is already obvious from the parameter name.

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 resource (logo/icon URL) and scope (for a domain, sourced from the company's own site), which clearly separates it from siblings like company_profile and company_suggest. It doesn't explicitly name a sibling, but the resource is distinct enough for an agent to route correctly.

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?

There is no when-to-use guidance, no prerequisites, and no comparison to alternatives. The parenthetical '(Clearbit Logo replacement)' hints at positioning but gives no condition for selecting this tool over company_profile or an external logo service.

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