cos_health

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds value by disclosing the exact statistics returned and noting the return type (JSON string with keys tables, schema_version, fts5_available, db_size_bytes, rag). This goes beyond annotations and helps the agent understand the tool's output.

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 front-loaded: a one-line summary, a usage sentence, and a Returns block. There is no redundant filler. The Returns block is slightly redundant given the output schema but provides immediate clarity for the agent.

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 zero-parameter, read-only health-check tool, the description is complete. It covers what the tool does, when to use it, and what it returns, while annotations cover safety and idempotency. No gaps are evident, and the output schema and return key list make the contract clear.

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 input schema has zero parameters, so description cannot add meaning beyond the schema. Baseline for 0 params is 4, and the description correctly does not invent parameter details. It does not confuse the agent about arguments.

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 that the tool returns database health stats, listing specific metrics (row counts per table, schema version, DB size, FTS5 availability, embeddings status). This is a specific verb+resource combination that distinguishes it from sibling tools focused on tasks, graphs, and retrieval. The phrase 'verify the thinking_os database is operational' reinforces its purpose.

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 explicitly says 'Use this tool to verify the thinking_os database is operational and to get a quick summary of stored data volume,' providing clear context on when to use it. It does not mention alternatives or exclusions, but for a health-check tool with no parameters, this is sufficient.

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