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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds the 'public thread' scope constraint and the compact option, but does not disclose auth requirements, rate limits, or return format details. With annotations carrying the main behavioral burden, a 3 is appropriate.

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 tightly written sentences: the first front-loads the core use case, the second efficiently lists alternatives with their conditions. Zero waste, easy to parse.

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 read operation with full schema coverage, no output schema, and comprehensive annotations, the description provides everything needed: purpose, usage conditions, and alternatives. Nothing critical is missing.

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%, so both parameters are fully documented in the schema. The description only restates the optional compact form without adding syntax, format, or behavioral nuance beyond what the schema already provides.

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 states a specific action (read thread content) on a specific resource (public thread UUID), and explicitly distinguishes itself from siblings by naming alternatives. An agent can immediately tell what this tool does and when it is appropriate.

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?

The description provides explicit conditions: use when you already know the thread UUID, prefer commons_thread_seed for a smaller continuation handoff, commons_search when the identifier is unknown, and commons_resume for bounded changes since a cursor. This is thorough routing guidance with no ambiguity.

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