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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), and the description adds real behavioral context: re-encoding to square PNGs, where the logo surfaces (header, switcher), size/format limits, auth prerequisite, and idempotency guidance. The boilerplate tail ('Canonicality', 'Idempotency', 'Confirmation boundary') is generic and slightly at odds with the earlier 'confirm with the founder' instruction, which muddies rather than clarifies.

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?

The first half is front-loaded and tight, but three templated paragraphs on canonicality, idempotency and confirmation boundaries are generic filler that does not earn its place and dilutes the actionable guidance.

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 still covers prerequisites, accepted formats, size limits, input-selection policy and downstream effects, which is enough for an agent to call it correctly. Only the return/result shape is left implicit, and the confusing confirmation-boundary boilerplate slightly weakens completeness.

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 67% and the schema already documents both image params, so the description doesn't need to restate them. It adds genuine selection semantics beyond the schema: prefer imageUrl for public https files vs imageBase64 for small local files, and the 5 MB / format constraints.

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 verb+resource ('Set or replace the company's logo') and names the accepted input forms, which distinguishes it cleanly from the sibling remove_company_logo. An agent can tell immediately what this does without opening the 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?

Explicit routing rules: prefer imageUrl for a public https link, use imageBase64 only for a small local file the founder chose; plus process guidance to confirm with the founder and ask once before inventing anything. Names when-not (SVG refused, ask for PNG export) as well.

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