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

Annotations carry no hints (readOnlyHint=false, etc.), so the description bears the full burden. It does disclose pricing (0.01 USDC/query) and a session cap (max 20 queries/session), but omits the on-chain transaction mechanics implied by open_tx_hash, proof_escrow_id, and buyer_address, and does not explain session creation side effects.

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 short and front-loaded with the core purpose, but the embedded 'Listing: registerwatch: The Register — Enterprise IT & Sysadmin Headlines (0.01 USDC/query (max 20 queries/session))' is a niche detail that obscures generality and reads like catalog metadata rather than tool guidance.

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 6 parameters, no required fields, no output schema, and a non-trivial session-opening workflow (funding, escrow, tx hash), the description is incomplete. It leaves an agent without guidance on how to provide open_tx_hash or proof_escrow_id, what the response contains, or how to proceed with funding.

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 only 50%, and the description does little to compensate. It references 'max 20 queries/session' but conflicts with the schema's max_queries maximum of 50, and it offers no explanation for open_tx_hash, proof_escrow_id, or how listing selection relates to listing_id/listing_slug.

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 with 'Buy per-query access to live data listings', a specific verb and resource, and clarifies the workflow with 'Open a prepaid session, then fund and query'. It implicitly distinguishes itself from data_preview (free) and data_session_fund/query (later steps), though it hardcodes a single listing ('registerwatch') rather than indicating generality.

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 explicit sequencing: 'first taste free via data_preview' then 'Open a prepaid session, then fund and query'. This tells an agent when to use this tool relative to sibling tools, though it does not mention exclusion cases or alternatives like data_session_attach_escrow.

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