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

Beyond the annotations (which only declare read-only, idempotent, non-destructive, open-world), the description discloses the exact return shape (data.artifact as a JSON string), a verification protocol for hashing the inner bytes versus data.digest, a warning not to reserialize, the immutability of priceCredits, the fact that downloading never installs or executes code, and the key scope required ('a key with read'). That is substantial behavioral context an agent could not infer from structured fields.

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?

Purpose and return semantics are front-loaded, and nearly every sentence carries operational information (hash protocol, priceCredits caveat, no-execution guarantee, auth scope). It is dense and somewhat jargon-heavy ('SIGN-IN-WITH-X', 'supplied application handoff'), but no sentence is clearly filler.

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 2-parameter read tool with no output schema, the description does the heavy lifting on return values and verification, which is the harder half. However, it leaves both input parameters completely unexplained, so an agent still cannot tell what a valid 'reference' looks like or when 'version' should be supplied.

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 description coverage is 0%, so the description bears the full burden for the two parameters, yet neither 'reference' nor 'version' is mentioned, nor are their formats, length limits, or how a reference relates to a version. Only the vague hints 'previously acquired' and 'your preselected digest' gesture at how a reference is chosen.

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 opens with a specific verb and resource ('Read a source implementation') and immediately scopes it to artifacts 'previously acquired by this account', which cleanly separates it from the sibling acquire_daystruct_package. An agent can tell which of the two tools it needs without opening either schema.

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 gives concrete usage context ('Review the source and follow the supplied application handoff in your authorized project. Validate integrated behavior and local adaptations') and names an alternative path for wallet owners (re-download over REST with SIGN-IN-WITH-X). What is missing is an explicit precondition stating that acquire_daystruct_package must run first when the artifact is not yet acquired, which is only implied.

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