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

Annotations already declare readOnlyHint and idempotentHint, so re-stating "Read-only" adds little, but the description goes further by disclosing the content of the response (full rule detail including the AST condition) and anchoring it to the CLI command and HTTP endpoint of record. That equivalence is genuinely useful context an agent cannot derive from annotations, though error behavior for a missing code is unstated.

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?

A single sentence front-loads the verb, resource, and lookup key, then appends the returned data and the CLI/API anchors; the trailing "Read-only" is short and functional. No sentence is wasted or padded.

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 one-parameter read tool with no output schema, the description tells the agent what entity is fetched and roughly what the payload contains (AST condition, full detail), which is enough to call it correctly. Only the failure mode for an unknown or ambiguous code is left unaddressed.

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% and the sole code parameter already documents its format and case-insensitivity, so the description cannot and does not add much beyond echoing "by code." Baseline 3 is appropriate when the schema fully carries parameter semantics.

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?

"Show one rule's full detail by code" gives a specific verb (show), a singular resource (one rule), and the lookup key, which cleanly separates it from the plural sibling list_rules. It also names the exact payload returned (the AST condition), so an agent knows what it will get without opening the 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?

Usage is implied by "one rule ... by code" and by "Read-only," which tells the agent this is the safe inspection path rather than a mutation like apply_config_change. However, the description never explicitly says when to use this instead of list_rules, explain_block, or check_sql, and gives no prerequisites or behavior for an unknown code.

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