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

The description adds substantial behavior beyond the annotations: calling it changes nothing, it returns a preview and a confirmation link, and only the merchant on that page can complete the change. That is exactly the non-obvious context an agent needs. There is a mild tension with readOnlyHint=false, since 'calling this changes nothing' reads like a read operation, though the preview/link flow plausibly justifies the write annotation.

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 core sentences are tight and front-loaded, but the 'Money is integer minor units (cents)' sentence does not earn its place: no monetary parameter exists in the schema, so it is dead weight that may induce a wrong invocation.

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 two-parameter mutation-like tool with no output schema, the description covers the important flow: preview semantics, confirmation link, and who can actually execute the change. The only real gap is the unaddressed relationship to sibling gift-card tools, and the stray money note.

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%, so the schema already documents both parameters, including that 'card' accepts a code with or without dashes or an id, and that status is an active/disabled enum. The description restates the status effect in prose but adds no syntax or format detail beyond the schema, so the baseline of 3 applies.

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 opening clause states a specific verb and resource ('Withdraw a gift card, or put it back'), which cleanly separates it from the sibling gift_cards_create. However, the sentence 'Money is integer minor units (cents)' implies an amount parameter that does not exist in the schema, which can mislead an agent about what the call actually requires.

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?

Usage is implied rather than stated: the description explains the effect of each status value ('disabled withdraws it so nobody can spend it; active puts it back'), which tells the agent what each mode does. It never says when this tool is preferable to alternatives such as gift_cards_create, and contains no explicit exclusions or prerequisites.

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