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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the bar is lower. The description still adds real value: 'No AI-credit charge' is a billing-side-effect disclosure not captured anywhere in the structured fields, and the awaiting_credit explanation describes resumability. It does not describe how statuses progress or how costly a polled read is.

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?

Roughly three sentences, front-loaded with the verb and return payload, then the state caveat, then the call-site instruction. Every sentence carries non-redundant information; no 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?

An output schema exists, so the description needn't spell out return values, and annotations cover the safety profile. For a two-parameter polling read, the main remaining hole is the unexplained definition_id/run_id pairing.

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% for both required parameters, so the description carries the full burden and does not meet it. run_id is only implied by 'one period report run,' and definition_id is never mentioned at all, leaving an agent to guess the relationship between the two identifiers.

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 a specific verb and resource ('Read one period report run') and enumerates what it returns: status values, coverage counts and cost. It never names sibling tools like get_period_report or list_period_reports, so an agent must infer the distinction from the singular phrasing.

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?

'Poll this after start_period_report' gives explicit when-to-use guidance tied to a concrete trigger. It also clarifies the awaiting_credit state ('resumes once credit or the limit allows'), but offers no when-not guidance or explicit comparison to the similarly named report-reading siblings.

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