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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, closed world), so the bar is lower. The description does add real context beyond them: party-only access and the accepted-thread precondition. But 'plus how it is redeemed' dangles without delivering, and the closing sentences are legal boilerplate rather than behavioral disclosure.

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 purpose is front-loaded in a single efficient clause, which is good. But the remaining half is disclaimer text ('Not affiliated with any store, brand or platform. HaggleBoard is not a party to any sale.') that does nothing to help an agent select or invoke the tool.

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 output schema and no parameter documentation, the description needed to explain both what buyer_token is and what comes back (a token string? redemption instructions?). It does neither, and 'plus how it is redeemed' is ambiguous about whether redemption guidance is a return value or just commentary.

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 0%, so the description carries the full burden for two required parameters and fails. thread_id is only obliquely hinted at by 'an accepted thread'; buyer_token is completely unexplained — the agent cannot tell whether it is the caller's credential, a token from a prior call, or the buyer's identity proof.

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 a specific resource (a signed Ed25519 deal token) and its scope (an accepted thread), which is enough to distinguish it from siblings like accept or list_offers. It stops short of explicitly routing the agent away from any named alternative, so it isn't a 5.

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?

'Party-only' and 'for an accepted thread' imply preconditions (you must be a participant, and the thread must already be accepted), which is useful implied usage guidance. However, there is no explicit statement of when to call this versus accept/list_offers, and no clear exclusion or failure condition spelled out.

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