get_promo_code

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

With no annotations, the description carries the transparency burden. It states 'Read-only, safe to retry' and 'Returns 404 if any of store_id, promo_rule_id, or promo_code_id is invalid.' It also mentions authentication and concurrency limits. This is good but could include more details on error handling or rate limits.

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 concise and well-structured: a clear purpose sentence, usage guidelines, behavioral notes, error handling, and then parameter/return lists. It front-loads the key information and avoids unnecessary words.

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?

The description covers purpose, usage, behavior, and return fields. It mentions authentication and concurrency limits. With an output schema present, the list of return fields is sufficient. However, it lacks details on possible error codes beyond 404 and does not specify which API key is needed. Overall, it is nearly complete for a read-only retrieval tool.

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 0% (no descriptions in schema). The description provides 'Args:' with one-line definitions like 'E-commerce store ID.' This adds minimal value beyond the parameter names. No format constraints or examples are given. The description should compensate for the lack of schema descriptions but fails to do so.

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 clearly states the tool's purpose: 'Retrieve a single promo code by ID with its current settings and usage stats.' It specifies the resource (promo code), the action (retrieve), and distinguishes from siblings like 'list_promo_codes' by indicating it is for a single code.

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?

Explicit usage guidance is provided: 'Use to check a code's usage_count before a campaign, or confirm a code is enabled. Use list_promo_codes to browse codes for a rule.' This clarifies when to use this tool versus alternatives, and also mentions authentication and concurrency limits.

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