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 by structured data. The description adds that results are scoped to the current user's plan and mentions a 'plans page' destination, which is mild extra context. It does not discuss caching, freshness of counters, or what happens when the plan lookup fails, so it adds only modest value beyond annotations.

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?

Two sentences, front-loaded with the outcome and followed by the trigger condition. The list of returned counters is dense but purposeful. The trailing phrase 'with the plans page' is slightly vague and could be clearer about whether it returns a URL, but it is not wasteful enough to hurt the score much.

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 zero-parameter read tool with full annotation coverage, the description covers purpose, scope, returned fields, and a trigger condition. No output schema exists, yet the description enumerates the key return values, which compensates well. The only gap is that it does not say what a quota-exhausted response looks like or how to interpret 'reliable builds.'

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?

There are zero parameters, so the baseline is 4; nothing about inputs needs explaining. The description correctly implies the tool operates on the implicitly authenticated user rather than taking a user or workspace argument, which is useful framing.

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 and resource ('Shows the user's PCBEditor plan') and enumerates exactly what is returned: monthly credits and renewal date, reliable builds, premium routing usage, and AI-tool jobs. It is clearly distinguishable from siblings like get_job or list_designs, which operate on individual resources rather than account-level quotas.

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 an explicit trigger condition: 'Use it when the user asks what they have left or a job stops at a plan limit.' That second clause is a strong diagnostic cue that routes quota-failure situations here. It does not name a specific alternative tool to prefer for related questions, but the usage context is concrete rather than implied.

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