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

With no annotations, the description carries the full burden and does useful work: it discloses merge behavior ('everything else in the link is kept') and names both return values (share_url, embed_url) and their intended use. It stops short of stating error behavior, permission/auth needs, or that the operation has no side effects.

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?

Three dense sentences with zero padding; the two usage modes are front-loaded and the return contract is appended last. Every clause adds information an agent needs.

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 an 8-parameter, nested-object tool with no output schema, the description covers both invocation modes, the partial-merge model, and the return values. Remaining detail (enum values, config keys, validation errors) is handled by the schema, so nothing critical is missing.

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 75%, so the schema documents most parameters, but the description adds real meaning: look is a preset starting point, share_url is the alternative starting point, and 'pass only the settings to change' explains the merge semantics of config. It clarifies the mutual-exclusion model that the schema only hints at.

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?

Names a specific verb (build) and resource (Globestudio URLs for a customized globe), and clarifies the two input modes. It implicitly distinguishes itself from read_share_url by framing share_url as a link to 'change' rather than read, but it never names a sibling explicitly, so it falls short of the top tier.

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?

Explicitly states the two entry points: start from a preset via look, or modify an existing link via share_url, and instructs to pass only the settings to change. It gives clear context but does not mention alternatives such as read_share_url, preview_url, or embed_snippet, nor any exclusions.

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