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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is fully covered without help from the description. The description adds return-content scope that annotations cannot convey: the response is limited to handle, plan, and coverage consumed in the current month. It adds no note on auth expectations or what 'coverage' is measured in, keeping it below 5.

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?

A single sentence after the title, front-loading whose account it is and then the fields returned. Every clause earns its place with no restatement of the title or name.

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 no-argument read tool with no output schema, the description is nearly sufficient: it names the three returned data points, so an agent knows what it gets back. Minor gap: it doesn't indicate value formats or units (e.g., what 'coverage used this month' means numerically), which matters slightly given the absence of an output schema.

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 declares zero properties, so there are no parameter semantics to explain and the baseline of 4 applies. The description reinforces this implicitly by describing a self-scoped retrieval with no identifiers to supply, which correctly tells the agent it cannot target a different user.

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?

States the specific resource (the signed-in reader's DataSnack account) and enumerates the fields surfaced: handle, plan, and monthly coverage. An agent can distinguish this from siblings like get_export or get_model, which retrieve artifacts rather than the caller's own profile. It never names an alternative explicitly, so it stops short of a 5.

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?

Usage is only implied: 'the signed-in reader's' signals that this needs no arguments and returns the caller's own account, which is adequate for a zero-parameter tool. There is no explicit when-to-use or when-not-to-use guidance (e.g., being the first call to establish plan/entitlement context), nor a named alternative for looking up other accounts.

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