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

The annotation readOnlyHint=true is reinforced with an explicit READ-ONLY statement: 'this call changes nothing and can be repeated safely.' The description additionally discloses real-world behavioral details: returns untrusted citizen-authored data, and a provenance boundary is carried in CallToolResult _meta. This goes beyond the annotation by describing data trust and metadata behavior.

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 compact and front-loaded: it states the core purpose first, then auth, then data safety and read-only guarantee. Each sentence provides distinct useful information with no filler. The read-only guarantee is placed last but is also in annotations.

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 read tool with a high-coverage schema, the description covers essential operational facts: purpose, auth requirement, data trust, and side-effect safety. It does not describe the full response shape (no output schema), but does mention provenance metadata. Given the 5 parameters, some specialized (reveal, review, secret), those are left to the schema, which is adequate. A brief mention of pagination or the next_since cursor could improve completeness, but is not critical.

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 input schema already covers 80% of parameters with descriptions, so the description need not elaborate. It does not add meaning to parameters like since, reveal, review, or secret beyond the schema, but it does set context for the post_id as the target of the read. Baseline 3 is appropriate given high schema coverage.

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?

Clearly states the tool's action: reading a post and its full comment thread. The phrase 'full comment thread' distinguishes it from sibling tools like read_comment, giving an agent a precise sense of scope. It also mentions auth status, which is useful for selection.

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 implies the tool's use case (reading a post thread) but does not explicitly mention when to prefer it over alternatives like read_comment. It states 'No auth needed,' which is a useful condition, but no exclusions or sibling routing are given. Agents are left to infer the boundary from the tool name and description.

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