cos_presence_query

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

Beyond annotations (readOnly, idempotent), it reveals it reads specific files (".coding-os/<agent>/sessions/*.json"), applies SSOT rules in board_os.presence, and defines behavior when agent is empty (reports all registered adapters). This adds valuable operational detail without contradicting 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?

Four compact sentences: purpose, data source, empty-agent behavior, and usage context. No redundant phrasing; each sentence adds distinct information.

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 tool's single optional parameter and the presence of an output schema, the description sufficiently covers data provenance, rules applied, empty-agent semantics, and practical use. It doesn't enumerate all return fields, but that is handled by the output schema.

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 has 0% description coverage, so the description must compensate. It explains the empty-agent behavior ('every adapter registered... is reported') but does not explicitly define the expected format/identifier for a non-empty agent value. Thus, partial compensation.

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?

Description opens with 'Return per-agent presence state and live-session inventory,' a specific verb+resource statement. It details the data source (.coding-os sessions files) and clearly differentiates from sibling tools by focusing on presence/session inventory.

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?

States it is used by cos daily, CI gates, and the live-agents board UI to verify zombie sessions are gone after deploy, giving concrete use cases. Does not explicitly name alternative tools or exclusion criteria, but the usage context is clear enough.

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