postfix_queue_shape

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds the output shape (domains as rows, age buckets as columns) and the diagnostic purpose, but says nothing about cost, queue-state requirements, or that deferred queues are the default focus.

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 tight sentences with no filler, and the matrix layout is stated before the diagnostic payoff. Every clause carries information; only the omitted sibling routing keeps it from being fully front-loaded for selection.

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 an output schema present, the description needn't explain return values, and the annotations cover the read-only nature. Its coverage of what the tool computes and when it's useful is adequate for a zero-required-parameter read tool, though an indication of how it differs from postfix_queue_summary would complete it.

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 100%, so all three parameters (by, top, queue) are already documented in the schema. The description corroborates the recipient/sender distinction for 'by' and the age-bucket dimension, but adds no syntax or default information beyond the schema; baseline 3 applies.

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?

Names the specific resource (a queue) and the operation (producing a qshape-style domain×age-bucket matrix), plus the diagnostic intent ('which destination is backing up and since when'). It is distinguishable from postfix_queue_list/summary by its explicit focus on age buckets, but it never names a sibling to route against.

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 implied by the outcome phrase 'Shows which destination is backing up and since when', which tells the agent the diagnostic question this answers. There is no explicit when-to-use vs. postfix_queue_summary or postfix_queue_list, and no stated prerequisites, so it stays at implied guidance.

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