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

With no annotations, the description discloses a key behavior: absence raises an exception due to unproduced date or pre-chain start. This adds meaningful error-handling context beyond the schema. It doesn't mention auth or rate limits, but for a simple getter, the provided behavior is a solid baseline.

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 exactly two sentences: the first states the core function and parameter format, the second covers edge-case behavior. Every word earns its place, with no fluff or repetition of schema details.

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 simple getter with one parameter and no output schema, the description covers purpose, parameter format, and error behavior, which is largely complete. A slight gap is the absence of detail about the proof envelope structure, but given the simplicity, this is a minor omission.

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 only defines date_str as a string, but the description adds the ISO YYYY-MM-DD format, making the parameter fully understood. Since schema coverage is 0%, the description fully compensates, leaving no ambiguity about the required input format.

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 specifies the tool returns an Ed25519-signed daily snapshot for a given date, using a specific verb ('Return') and resource. It distinguishes itself from siblings by focusing on 'signed snapshot' and the date parameter, differentiating from verify_snapshot_signature and get_mpt_snapshot.

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 provides clear context: use for retrieving signed daily snapshots, and notes absence raises an error for future or pre-chain dates. While it doesn't explicitly name alternatives, the sibling tools' names imply distinct purposes, and the description contexts are sufficient for an agent to choose appropriately.

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