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

With no annotations, the description carries the full burden and mostly does: it discloses that the counterparty exposes agent_card_url only when published, that accepted_terms is a read-only snapshot frozen at accept, that accepted_terms_sha256 is the hash of its canonical JSON, and that these are null on older deals. That is meaningful edge-case behavior an agent would otherwise have to discover empirically. It omits error/not-found behavior and auth requirements beyond what the schema implies.

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?

Three dense sentences, front-loaded with the core purpose, then counterparty/A2A guidance, then the accepted-terms fields. Some domain jargon (canonical JSON, A2A) but no filler sentences; each one adds information.

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?

There is no output schema, so the description must characterize the return payload, and it does: negotiation thread, counterparty object, and the accepted_terms/accepted_terms_sha256 pair with their null semantics. For a two-parameter read tool this is close to complete, though it does not describe thread shape or what an unaccepted bid's fields look like.

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% with only two parameters (bid_id and api_key), both documented in-schema. The description adds no format or interpretation detail for either, so the baseline 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?

States a specific verb+resource: 'Bid detail with the full negotiation thread' tells an agent this retrieves a single bid plus its message history, distinguishing it implicitly from list_bids/list_my_bids. It stops short of naming a sibling explicitly, so it lands at 4 rather than 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?

The description embeds workflow advice ('for long talks negotiate over A2A directly and mirror the final terms into one proposal here'), which implies this tool is for reading/inspecting a bid. But it never states when to call this versus list_bids, get_intent, or accept_bid, and offers no exclusions or prerequisites.

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