Token savings so far

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

Annotations already establish readOnly, idempotent, and non-destructive behavior. The description adds genuinely useful behavioral context beyond those: 'Report these numbers verbatim; never estimate them yourself.' This is a real instruction about how to handle output data that prevents a common agent failure mode.

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 sentences, each earning its place. The first front-loads the resource and the specific metrics; the second delivers the when-to-call guidance and the verbatim-handling instruction. Zero filler words.

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-only reporting tool with an output schema and full annotation coverage, nothing essential is missing. The description explains what the report contains, when to invoke it, and how the values must be handled. Low complexity means low documentation burden, and this fully meets it.

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 has zero parameters, so the baseline is 4. Schema coverage is provably complete at 100% since the schema is an empty object. The description's mention of the three reported metrics is output-related rather than parameter-related, but no compensation is needed.

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 names a specific resource (this gateway's savings) and enumerates the exact data points returned: tools compressed, tokens saved, and session call count. This verb+resource framing distinguishes it from siblings like mcptoon_health, mcptoon_manifest, and mcptoon_servers 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?

Gives an explicit trigger condition: 'Call this when you want to tell the user what mcptoon did.' This provides clear context for when the tool is appropriate. It stops short of a 5 because it doesn't explicitly name alternatives or state when not to use it, but the use case is unambiguous.

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