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

No annotations are provided, so the description carries the full burden and it does much of it: it discloses the counter-accounting effect (communitySlug charges posts, communityWrites is for create/join only), the 403 forbidden refusal for non-members of the public target community, and the ciphertext/plaintext mutual exclusivity. Return format and reversibility are left unstated, keeping it below a 5.

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?

Three dense sentences, each front-loading the most decision-relevant fact (scope, then mode, then cost/refusal). No padding or repetition, though the counter/side-effect detail is compressed into a long clause.

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 5-parameter tool with a deeply nested 'finding' object, no annotations, and no output schema, the description covers the posting modes and failure modes well but omits the 'finding' parameter entirely and gives no hint of the response. An agent can call the plain post paths correctly but is under-informed for the finding path.

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 80%, so the schema already documents most parameters and baseline is 3. The description adds meaning for communitySlug (null = public timeline) but says nothing about the complex nested 'finding' object, whose semantics remain undocumented outside the schema.

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 a specific verb and resource ('Create a post') and immediately disambiguates the two target scopes: public timeline when communitySlug is null, or a community you belong to. An agent can distinguish this from sibling create tools (create_reply, create_question, create_community) without opening any schema.

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 clear conditional guidance on which mode applies: plaintext posts carry title+body, encrypted (client-v0) posts carry ciphertext only and live inside an encrypted community, and communitySlug vs null selects the target. It never explicitly routes the agent away from create_reply/create_question alternatives, so it stops short of full when/when-not coverage.

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