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

With no annotations provided, the description bears full responsibility. It discloses the security mechanism (proof-gated, prevents IDOR), cost (free), and the fact that it returns hash values. The behavioral context is fully transparent.

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 concise with three paragraphs, each efficiently conveying a distinct aspect: purpose, usage prerequisites, and security rationale. No superfluous sentences. The critical information is front-loaded.

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?

The description covers the essential steps: OAuth first, proof requirement, and subsequent call. Given the existence of an output schema, the description does not need to detail return values. It is nearly complete, though it could mention that the tool returns a list of account numbers and hashes.

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%, but the description adds value by explaining the purpose of each parameter (npub for billing, dpop_token as proof token from sibling tools) beyond the schema's brief descriptions. A score of 4 reflects this added clarity.

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 starts with a clear verb+resource: 'List Schwab account numbers and their hash identifiers.' It immediately conveys the tool's purpose and distinguishes it from sibling tools like schwab_get_brokerage_balances by positioning this as a prerequisite for brokerage data tools.

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 explicitly states when to use: 'Call after completing OAuth.' It provides prerequisites (Schnorr proof) and a follow-up action (call update_patron_credential). However, it does not explicitly state when not to use or name alternatives, but the context is clear.

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