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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description goes beyond them by naming the data domains returned (website, summary, documents and their status) and by disclosing that mutation happens outside this tool, in the OsmO app. It does not describe freshness or size of the returned Facts, which keeps it short of a 5.

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 short sentences with zero waste, and the substantive content (what the Facts comprise) is placed first, with the read-only constraint and the routing note after it.

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 no output schema, the description supplies enough: it enumerates the fields an agent will receive and explains that edits happen elsewhere. A slightly fuller explanation of the payload shape would be needed for a 5, but nothing essential is missing for correct invocation.

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?

The tool takes zero parameters, so there is no parameter meaning to add and the schema baseline of 4 applies. The description correctly spends no words on inputs.

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 resource (the Facts the assistant answers callers from) and enumerates what those Facts contain: website, summary, documents and their status. That is far clearer than a bare 'get_facts', though the description never contrasts it with siblings like get_assistant or get_settings, so an agent must infer that this is specifically the knowledge base.

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?

The line 'Read-only; Facts are changed in the OsmO app' effectively rules out using this tool for editing and points at another surface, which is useful context. However, it gives no explicit guidance on when to reach for get_facts versus get_assistant or get_settings, so the choice is implied rather than stated.

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