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

Annotations declare it is not read-only, idempotent, non-destructive and open-world, but the description adds the substantive context annotations cannot convey: no additional credit cost, the Maintain-subscription precondition, the x402 exemption, and the token cost of inline delivery. Nothing here contradicts the annotations (readOnlyHint=false is consistent with a tool that mints a fresh clone credential).

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?

Front-loads what the tool does and the no-cost guarantee, then moves to preconditions and delivery modes. The dense em-dash phrasing and parenthetical asides make some sentences heavy, but no sentence is filler.

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 3-parameter tool with no output schema, the description covers the return shape (a git clone command vs. files in the reply), the credit implication, and the authorization preconditions. An agent has everything needed to call it correctly.

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 100%, so the baseline is 3, but the description goes beyond the schema by explaining that projectid is resolved from the authenticated account and by framing delivery as a token-cost tradeoff rather than just an enum. The site_profile guidance largely restates the schema, so it is not a full 5.

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 and resource ('re-fetches a scaffold you already purchased') and immediately distinguishes itself from the sibling purchase_scaffold by naming the prior-purchase precondition. An agent can tell it apart from purchase_scaffold and verify_scaffold without opening any 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?

Explicitly scopes use to scaffolds already purchased, names the originating tool, and lays out the conditional gates (active Maintain subscription required for credit-flow projects; no gate for x402/accountless projects) with a pointer to set_projects. It also names the alternative path implicitly by framing this as a repeat hand-off rather than a purchase.

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