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

Annotations already cover readOnly/idempotent/openWorld, so the description goes beyond them usefully by disclosing the data source (NearBlocks indexer), the auth model (no API key, prepaid x-credit-token header, 1 free call/day), and the price ($0.02 per call over x402 on Base). These are real selection-affecting facts an agent can't get from annotations.

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?

Front-loads the purpose in one sharp question, then consolidates outputs, pricing, and input requirements into a tight block. Slight redundancy: the output is described twice (the full enumeration and the 'one-line summary plus the last 10 transactions'), and 'Required input: account' merely repeats the schema.

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 a two-parameter read tool with full schema coverage, an output schema, and safety annotations, the description supplies everything else that matters: what the data source is, what the response contains, pricing/rate-limit model, and the account requirement. Nothing needed to invoke it correctly is missing.

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 coverage is 100%, so the baseline is 3. The description adds the one thing the schema omits — that limit defaults to 25 — plus framing that limit governs 'recent transactions,' which is genuinely additive rather than restated from the schema's optional/5-50 note.

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?

Opens with a concrete question framing a specific verb+resource ('Recent history of a NEAR account, summed up') and enumerates the exact content returned: txns signed/received, failures, NEAR flows, per-token flows, top contracts, top counterparties, and signals. It never names the adjacent siblings (near_portfolio, near_account, wallet_activity) so differentiation must be inferred from the feature list.

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 operational context (reads the NearBlocks indexer, limit defaults to 25, $0.02 per call via x402, free tier of 1 call/day) but never states when to pick this over near_portfolio, near_account, or wallet_summary. Usage is implied by the feature enumeration rather than explicitly routed.

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