suggest_gsi

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

With no annotations, the description carries the full burden. It discloses a key behavioral trait: the tool checks existing indexes and returns alreadyIndexed: true with an existing index name rather than proposing a duplicate. It also implies no mutation by saying 'generates a definition.' It could add more on error behavior or persistence, but overall it provides strong transparency.

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 sentences: main purpose, when to use, and key behavior with an alternative. Front-loaded and no filler. Every sentence earns its place.

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 2-param tool with no annotations and no output schema, the description is thorough. It explains what is produced, the alreadyIndexed special case, and points to get_table_schema for more information. This is sufficient for an agent to select and invoke correctly.

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%, so baseline is 3. The description reinforces the meaning of 'attribute' as the index key and adds context on how table and attribute are used together, including the duplicate check behavior. This adds value beyond 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?

The description uses a specific verb ('generates') and resource ('DynamoDB GSI definition'), and clearly distinguishes from sibling tools like postgres_index_suggestions and get_table_schema by naming DynamoDB and the exact output components (index name, partition key, projection type, billing mode). The alreadyIndexed behavior further differentiates it.

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 states when to call: 'when a query pattern needs an index that does not exist yet, or when the analyzer flags a missing GSI finding.' Also names an alternative: 'Use get_table_schema for the full index list on a table.' This provides clear context and exclusion.

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