session.get

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

Annotations already declare readOnlyHint=true, and the description's 'Read-only' restates that rather than adding to it. It does add real value beyond the annotation by bounding the payload (what the record does NOT contain) and naming the fallback tool for the missing data, but it says nothing about pagination, timestamp format, or failure behavior for a bad session_id.

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 sentences, front-loaded with the return payload, then safety, then the negative-scope handoff. Nothing is padded and the field enumeration earns its place because there is no output schema.

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?

With one optional parameter, no output schema and a readOnly annotation, the description covers enough to call the tool correctly and even lists return fields. Minor gaps remain (no status value ranges, timestamp format, or error behavior for an unknown session_id).

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 the schema already says 'omit for the project's active session', so the description's default-behavior line is largely a restatement. Baseline 3 is appropriate since the schema carries the parameter meaning.

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 ('Return the session record as JSON') and enumerates the returned fields, so the agent knows exactly what it gets. It also explicitly separates itself from context.get/context.read, which carry decisions, blockers and next action.

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?

Gives the routing rule explicitly: use this for the session record, use context.get (or context.read in a read-only client) for decisions/blockers/next action. It also states the default when no session_id is supplied, so the agent can call it with zero arguments knowingly.

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