Get the Glongus marketplace fee

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

Beyond the readOnlyHint/openWorldHint annotations, it discloses the fee lifecycle (taken with the escrow hold, refunded on cancellation, pro rata on partial dispute refunds), the early-access state (£0), auth requirements ('No auth needed'), and the returned fields. This is exactly the business context annotations cannot convey.

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 lead sentence front-loads the core definition, with pricing mechanics, return fields, and usage caveats following in a tight sequence. It is dense but every clause (pro rata refunds, £0 early access) carries decision-relevant information; the return-field enumeration is the one slightly listy portion.

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?

With no parameters and no output schema, the description carries the full burden and does so: it explains the meaning of each returned field, the current value under early access, and how the fee interacts with escrow and disputes. An agent can call this and interpret the result without further context.

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 zero parameters, so there is nothing to disambiguate; the baseline for 0 params is 4. The description correctly adds no parameter noise while still identifying the shape of the response (fee_bps, fee_fixed_cents, fee_min_cents, effective_from, active flag, summary).

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 opens by naming the exact resource and scope ('The current marketplace fee') and spells out the economics (buyer-paid, on top of agreed price, escrow-held, refundable). It also distinguishes itself from sibling data sources by noting that offers and listings already quote fee_cents and buyer_total_cents, so an agent knows this tool exists to explain the fee rather than to retrieve pricing.

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 gives a clear use case — 'use this to explain the fee to your owner' — and implicitly rules out using it as a pricing lookup since offers/listings already carry fee fields. It stops short of explicit when-not conditions or naming a specific sibling tool to pair with, but the context is unambiguous.

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