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

The description discloses several non-obvious behaviors: the hold is free and advisory, the seller is not obligated to honor it, OAuth scope is required, and deposit-backed holds are not yet available. This adds significant context beyond the annotations, which only indicate non-read-only, open-world, idempotent, and non-destructive hints.

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 description is front-loaded with the primary purpose and includes a useful example. The marketing sentence ('The first UK marketplace...') adds little functional value, but overall the description remains concise and well-structured.

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?

The description provides essential operational context: 24-hour duration, free/advisory nature, OAuth requirement, and deposit limitation. Since an output schema exists, return values need not be described. No critical gaps remain for a simple hold mutation.

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?

With schema description coverage at 50%, the description compensates by clearly explaining that depositGbp should be omitted because deposits are unavailable. It does not elaborate on listingId, but the parameter name is self-explanatory and the example implicitly illustrates its usage.

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 clearly states the tool's specific action ('Hold a Cyclesite listing') and its purpose ('so other buyers can't claim it while the user decides'), distinguishing it from siblings like publish_listing or mark_as_sold. The inclusion of a time frame (24 hours) makes the scope precise.

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?

The description provides clear usage context: when a user wants to temporarily secure a listing before deciding. It explicitly warns against offering deposits today and suggests messaging the seller to confirm, which is a practical after-step. However, it does not explicitly contrast with alternatives (e.g., make_enquiry) or name higher-level alternatives.

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