Read PG buffercache summary

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

Annotations already declare readOnlyHint=true, so the description's read-only nature is established. The description adds important behavioral context: the extension requirement and the available=false fallback, which go beyond the annotations.

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 extremely concise: two sentences that front-load the purpose and then add essential conditions. Every word adds value, with no redundancy.

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 simple read tool with one optional parameter, clear annotations, and an output schema (implied by context), the description covers the return values, extension requirement, and failure mode. It provides enough information for the agent to understand what to expect.

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?

The tool has one optional parameter (database) with schema coverage at 100% and a clear description in the schema. The tool description does not add any additional semantics about this parameter, so the baseline score of 3 is appropriate.

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 identifies the tool as reading a high-level summary of the PostgreSQL shared buffer cache, specifying the exact metrics (total, free, used, dirty buffers, average usage count). It distinguishes from the sibling read_pg_buffercache_relations by focusing on summary rather than per-relation stats, though this is not explicitly contrasted.

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 mentions the requirement for the pg_buffercache extension and the behavior if not installed (returns available=false), providing some context. However, it does not explicitly state when to use this tool over its sibling read_pg_buffercache_relations, leaving the usage guidance implicit.

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