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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint=false, so "Makes no external calls" largely restates structured data. What the description does add beyond annotations is the no-active-run fallback behavior and the exact contents of the response, which matter when there is no output schema.

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?

Three short sentences, front-loaded with the return contents before the runId fallback rule. Nearly every clause earns its place; the only wasted phrase is "Makes no external calls," which duplicates openWorldHint=false.

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 two-parameter read tool with no output schema, the description enumerates the return fields and covers the empty-state edge case, so an agent knows both how to call it and what to expect back. Nothing needed to invoke it correctly is missing.

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% and both parameters are already documented there, including "Defaults to the run in progress" for runId and "from list_sites" for projectId. The description only re-expresses the runId default in prose, adding no syntax, format, or ID-provenance detail beyond the schema, so 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?

"Returns the progress of a site's content calendar run" pairs a specific verb with a specific resource, and the colon-list (status, per-stage status/summary, topic count, times, stop message) makes the payload unambiguous. It is clearly a read-side counterpart to start_content_calendar and the calendar-topic mutation siblings.

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?

Explicitly states the two calling modes: with runId it reads that run, without runId it reads whatever run is in progress, and it pre-empts the empty case ("when none is in progress, the result says so"). It stops short of naming a sibling to use instead for historical runs or listing exclusions, so it is clear context without full alternatives guidance.

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