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

Annotations only declare readOnlyHint=true, and the description is consistent with that while adding real behavioral context the annotations cannot convey: the free-tier allowance concept and the budget-gating rule for non-free operations. It also hints at return content ('each with its exact input schema'), though it does not describe the shape of the listing or how to read the free markers programmatically.

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 sentences, all load-bearing: the first identifies the resource and its payload, and the last two are a compact if/then routing rule. The allowance rule is front-loaded ahead of the escalation path, with no redundant restatement of the name or title.

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?

This is a zero-parameter catalog tool with no output schema, and the description covers what an agent needs: what the list contains, that entries carry input schemas, and how to act on the free/budget distinction. The only gap is that it does not explain the entry structure (for example, how 'free' and the input schema are surfaced), which matters slightly more here because no output schema exists.

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?

The tool takes no parameters (empty properties object, 100% schema coverage), so there is no parameter semantics burden to carry. Baseline applies; there is nothing the description could add or omit here.

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 names the concrete resource (the catalog of services Gluo runs) and gives representative examples (site checks, screenshots, domain availability, email setup, dependency vulnerabilities), plus states that each entry carries its exact input schema. The listing verb is only implied by the tool name/title, not stated, so it falls just short of a clean verb+resource statement.

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?

It explicitly routes the agent to the right sibling: operations marked free go to call_api with no budget up to a daily allowance, and anything else, or anything over the allowance, requires request_budget first. This is exactly the when-and-which-alternative guidance an agent needs before choosing between list_services, call_api, and request_budget.

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