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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered elsewhere. The description adds the useful detail of what the response contains, but says nothing about auth requirements, behavior for keys without an active plan, or rate limits.

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 front-loaded clause names the resource first and then enumerates the payload; there is no filler. It is a fragment rather than a full sentence, but every element carries information and nothing is repeated from the schema.

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?

With no parameters and no output schema, the description correctly compensates by naming the returned fields, which is the key thing an agent cannot learn from structured data. It is close to complete for a trivial read tool, missing only a note on how it differs from list_plans.

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 tool takes zero parameters, so per the baseline a 4 applies. The parenthetical list of limits (API/day, MCP/month, watchlist, API keys) describes returned data rather than inputs, so there is no parameter semantics left to clarify.

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 states a specific resource and scope: the current plan of the key owner, plus exactly what is returned (name, status, period end, limits). It is clearly distinguishable in intent from upgrade_plan, but it never explicitly contrasts itself with the sibling list_plans, which a reader could plausibly confuse with it.

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 by the verb 'get' and the word 'current' — an agent can infer this is the single-plan fetch rather than the listing tool. There is no explicit when-to-use statement, no mention of prerequisites, and no routing note pointing to list_plans or upgrade_plan for related needs.

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