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

Annotations only cover the read-only safety profile, and the description adds genuinely new behavioral facts: "Nothing is run" (reading a report does not execute its query), the payload contents (name, type, widgetType, chartType, assignments, display settings, query id, url), Vega-Lite special-casing via chartProps.vegaLite with chartRevision and last-five chartHistoryNotes, and that spreadsheet-backed widgets carry their rows.

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?

Purpose is front-loaded in the first clause and nearly every clause carries a distinct fact. It is a dense single paragraph with heavily nested parentheticals ("its query (the id of the saved query it reads, whose SQL fastero_get_query returns) and url"), which costs some readability.

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?

There is no output schema, so the description bears the full burden of describing the return payload, and it does so thoroughly, including the Vega-Lite variant and revision history. Combined with the sibling routing, an agent has everything needed to call it and interpret the result.

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 already document their provenance (fastero_list_reports / dashboard items; fastero_list_projects). The description body adds no further parameter-level detail, so the baseline 3 applies — the schema carries this dimension.

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?

Specific verb plus resource ("Read one report"), and it immediately defines what a report is — "a chart, table, number, map or text block that dashboards place" — so the agent knows the object model. It distinguishes itself from the near-name siblings (fastero_get_dashboard, fastero_show_report, fastero_list_reports) by naming them and their distinct roles.

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?

Three routing alternatives are given: fastero_get_dashboard identifies which reports a dashboard places, fastero_show_report renders the chart itself, and fastero_get_query returns the SQL behind the referenced query. The selection conditions are implied by those roles rather than phrased as explicit "use X when Y", so it falls just short of a 5.

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