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

Beyond the annotations (readOnlyHint=false, destructiveHint=false), the description discloses important behavior: 'nothing is uploaded', the fingerprint is 'timestamped (RFC 3161), sealed on a public append-only ledger and anchored to Bitcoin', and it is 'Free, no account.' These details give the agent a clear picture of the tool's operation and effects, exceeding the minimal annotation information.

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 just a few sentences, front-loaded with the main action and key differentiator ('nothing is uploaded'). Every sentence contributes useful information—purpose, mechanism, ideal use case, cost, and limitation—without redundancy.

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 purpose, use case, behavior, and limitations comprehensively for a tool with no output schema. The only missing piece is what the caller should expect as a result (e.g., a certificate or receipt). Since there is no output schema, mentioning the return value would make it fully complete.

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?

The input schema already explains all four parameters with full coverage, including a highly detailed description of output_hash (exact bytes, line ending issues). The tool description adds the general concept of 'send only its SHA-256' but no new parameter-specific semantics beyond what the schema already provides. Baseline 3 is appropriate.

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 clearly states the tool's specific purpose: 'Prove content existed at a point in time WITHOUT revealing it: send only its SHA-256.' It uses a specific verb ('prove') and resource ('SHA-256 fingerprint'), distinguishes it from siblings by explaining it is not for authorship, and the title reinforces that nothing is uploaded.

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?

Provides clear when-to-use guidance: 'Ideal for private code, drafts or anything you must keep secret but want provable priority for.' It also explicitly states what it does not do ('Proves existence and time — not authorship'), which helps exclude it from authorship-related tasks. However, it does not name an alternative tool, so it lacks an explicit 'use X instead' pointer.

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