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

Annotations already declare openWorldHint=true, idempotentHint=false and destructiveHint=false; the description adds genuinely new behavior: the call blocks until a node accepts across a raced top-K set or times out, and it returns a sessionId. That latency/blocking and return-value disclosure is useful. It stops short of saying what a timeout leaves behind (session created? funds committed?) or what non-idempotent retries do.

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?

Two dense sentences that front-load the action, then funding, then return/blocking semantics — no filler. The clause 'Blocks until a node accepts (raced top-K) or times out' is compact but assumes the reader knows what 'raced top-K' means.

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 an 11-parameter, nested-object, open-world, non-idempotent session-opening call with no output schema, the description covers the essentials (two addressing modes, funding, sessionId return, blocking behavior). It leaves too much undisclosed for full confidence: over half the parameters are unexplained and there is no guidance on timeout outcomes, retry safety, or the requester/siwx identity requirements.

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% across 11 parameters, so the description carries the full burden; it explains offer_id, the spec fields kind/network/max_price/min_rep, market_id and payment, which is meaningful. However siwx, quota, raced, params, mandate, requester and the top-level deadline_secs are never mentioned, and the description renders max_price where the schema says max_price_near_per_unit, leaving ambiguity.

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 and resource ('Open a metered resource session') and immediately names the two mutually exclusive ways to identify the counterparty: a signed offer via offer_id or a routing spec via kind/network/max_price/min_rep. It also names the downstream sibling ('Returns sessionId for wide_request_call'), so an agent can place it in the workflow without opening another schema.

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?

Gives clear conditional routing between the two modes (offer_id vs. spec-based routing) and states the funding precondition variants ('market_id escrow or x402 payment; admin/testnet may omit'). It does not say when this tool is inappropriate — e.g. whether an offer must be discovered via wide_offers first, or whether an existing session should be checked via wide_request_status before opening a new one.

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