session_ping

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

With no annotations, the description carries full burden. It mentions it is 'extremely fast — one Redis SET, no blocking operations' and explains the checkpoint storage. However, it does not disclose overwrite behavior or authentication requirements. The behavioral transparency is adequate but not exhaustive.

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 description is a single front-loaded paragraph, approximately 70 words, with no redundant sentences. It efficiently communicates the tool's purpose, usage, and technical constraints.

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 simple checkpoint tool, the description explains when to use, why it's needed, performance characteristics, and failure recovery. It could mention that subsequent calls overwrite the previous checkpoint, but overall it is complete given the lack of output schema.

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 coverage is 100%, so the description adds minimal value over the schema. It mentions 'stores the current task + files touched' which maps to two parameters, but does not elaborate on the others (instance_id, next_step, provider). Baseline score of 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?

The description clearly states it is a 'lightweight checkpoint' to be called periodically or after significant steps. It distinguishes itself from siblings like session_start and session_end by focusing on storing task and files touched for provider-switching.

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?

Provides explicit guidance on when to call ('every ~5 tool calls or whenever you complete a significant step') and explains the purpose for provider-switching. It mentions the failure scenario where session_end may not be called. However, it does not explicitly list alternatives or when not to use.

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