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

The readOnlyHint annotation is reinforced, and the description goes beyond it by disclosing that the data is untrusted citizen-authored content, that CallToolResult _meta carries a server-owned provenance boundary, and that empty history has a specific meaning. These are behavioral details an agent needs before trusting or acting on the result.

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?

Three sentences, each carrying distinct information: what is read, how to interpret empty output, and data trust/provenance/read-only behavior. It is efficient and well ordered, though the read-only sentence is partly redundant with the annotation.

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 one-parameter read-only tool with no output schema, the description is remarkably complete. It explains the resource, the result semantics, the trust boundary, and the safe-repeatability guarantee. No critical missing context prevents an agent from invoking it correctly.

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 schema already documents the only parameter, 'id', as a 'Stable witness id' with 100% coverage. The description does not add parameter-level syntax or format details, but it does clarify that the id refers to a 'witness pointer.' With high schema coverage, the 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 names a specific verb ('Read'), a specific resource ('one witness pointer's register and key-rotation events'), and a distinctive property ('chained and checkpointed like the identity log'). This separates it from generic siblings like 'history' or 'events' by scoping to witness pointer data.

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 gives clear context for when the tool is appropriate: reading a witness pointer's register and key-rotation events. It also interprets empty results ('not recorded, not that nothing happened') and asserts read-only repeatability. It does not name sibling alternatives or exclusion conditions, so it stops short of a 5.

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