session_enter

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

Beyond annotations, the description discloses the side effect (registers/writes a session record), the conditional PR2 signature-verification behavior, the ordering guarantee (verification BEFORE record writing), and the structured-error behavior on invalid signatures. It also states when parameters are ignored, which is valuable behavioral context. No contradiction with idempotentHint=true.

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?

The most essential fact ('FIRST CALL') is front-loaded, the core behavior is compactly listed, and the second paragraph isolates the PR2 edge case without cluttering the main flow. Every sentence earns its place given the 8-parameter surface.

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 tool with no output schema and only basic annotations, it describes the full return orientation payload, the two entry modes, how to close the session, and the conditional auth branch. Missing details like duplicate-session behavior are already covered by idempotentHint=true.

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 0%, so the description must compensate. It explains dispatch_id, verifier, attested_at, and seal_sig meaningfully, and 'app/session pair' hints app_id/session_id, but project and workspace are left completely unexplained.

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 the verb 'FIRST CALL', resource (app/session pair), and scope (registers, resolves entry mode, returns orientation), explicitly positioning itself as the entry point to every session. This differentiates it from siblings like session_read or session_handoff_write without needing to open their schemas.

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 says to pass dispatch_id when entering to work an assigned packet and names the session-closing sibling tools for both the human and dispatch paths. It does not, however, articulate exclusions such as 'do not use for later reads' or what to do if the session already exists, leaving some usage inference to the agent.

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