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

Annotations already declare readOnly, idempotent, and non-destructive, so the bar is lower; the description still adds auth requirements (bearer session, recipient-bound capability), a precondition of non-expiry/non-revocation, and the failure-handling path. It doesn't quantify rate limits or return field detail, keeping it from 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?

Four compact sentences, front-loaded with the core action before prerequisites and error handling. Every sentence carries distinct information, though the failure clause is slightly dense.

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 single-parameter, read-only tool with full annotation coverage, the description covers what the agent needs: what it reads, where the capability comes from, auth preconditions, and what to do on rejection. The absence of an output schema is acceptable since it flags a read-only projection.

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% for the single access_capability param, so the schema already carries format (32-2048 chars) and secrecy guidance. The description's mention of its origin in share_cassie_note mostly restates the schema, so the baseline 3 applies.

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 precise verb and resource with scope: 'Read exactly one note shared with the authenticated recipient.' It distinguishes this from siblings like share_cassie_note and submit_cassie_note by tying the read to a recipient-bound capability produced elsewhere.

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?

Explicitly routes the agent to share_cassie_note as the source of access_capability and states the precondition (valid bearer session, unexpired recipient-bound capability). It also prescribes recovery ('ask the author to issue a fresh share') on failure, though it doesn't contrast against near neighbors such as get_public_story_record.

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