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

Annotations cover the safety profile (readOnly=false, idempotent=false, destructive=false). The description adds non-obvious context: the createToken enables a retryable create, the document capability must be kept private and reused in later calls, and resourceUri is host-bridge-only. It doesn't spell out the create-vs-resume parameter contract, but it adds real value beyond the annotations.

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 tight sentences with the prerequisite (rapier.guide) front-loaded. The trailing 'get_context reports editor presence' is slightly orphaned but still earns its place as a verification pointer. 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 return values need no explanation. With 6 parameters, 0 required and two distinct modes (create vs resume), the description should clarify which parameters belong to which mode and what happens if none are supplied; that gap leaves the agent under-informed for an open-world-free but stateful session tool.

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 83%, so the schema already carries most parameter meaning. The description only lightly touches the document capability ('resumes one by its document capability') and adds nothing about how file, text, docKind, filename and createToken combine into the create flow. Baseline 3 is appropriate.

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 specific verbs (creates/resumes) and a concrete resource (an editable workspace for document, drawing or review), so the agent knows this opens a session rather than editing content. It does not, however, differentiate itself from nearby siblings like document.open_text, which could be confused with the create path.

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?

It gives conditional guidance for a sibling ('call rapier.guide once first if your host gave no instructions') and points to get_context for editor presence. But it never states when to pick rapier.open over document.open_text or other creation entries, leaving the core selection decision implicit.

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