AWS MCP Server

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

With no annotations provided, the description carries the full burden. It discloses the read-only nature via 'Describe' and lists key return fields, but omits behavioral details like pagination behavior (how max_records functions), throttling considerations, or whether omitting replication_group_id returns all groups versus erroring.

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?

Two sentences with zero waste. The first front-loads the action and resource; the second efficiently describes the return payload. Every word earns its place with no redundancy or generic filler.

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?

Given the lack of an output schema, the description appropriately compensates by detailing the return structure (endpoints, node groups, failover settings). It adequately covers a read-only discovery tool's needs, though mentioning pagination or the 'list vs get one' behavior when replication_group_id is omitted would strengthen completeness.

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?

With 100% schema description coverage, the schema already documents all four parameters (profile, region, replication_group_id, max_records). The description does not add additional semantic detail like parameter interdependencies, valid ID formats, or that leaving replication_group_id empty returns a list rather than a specific record, meeting the baseline expectation.

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 ('Describe') and resource ('ElastiCache Redis replication groups') and adds helpful context with '(clusters with replicas)'. This distinguishes it from siblings like 'describe_cache_clusters' (individual nodes) and 'describe_serverless_caches' by specifying the exact topology, though it does not explicitly name sibling alternatives.

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?

The description implies usage by detailing what it returns ('primary/replica endpoints, node groups, and failover settings'), suggesting when to use it (when you need topology/failover data). However, it lacks explicit guidance on when to use this versus 'describe_cache_clusters' or prerequisites like requiring the replication group ID.

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