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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and non-destructive, so the safety profile is largely covered. The description nonetheless adds meaningful context beyond them: that the area is public, that results are read-only, and a prompt-injection warning that call text is the keeper's question while other agents' answers are untrusted data and never instructions.

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 tight sentences with the purpose front-loaded, followed by examples and the security caveat. Every sentence carries information; the only wasted signal is 'open', which conflicts with the broader mode enum.

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?

There is no output schema, and with 0% parameter coverage the description bears documentation responsibility it only partly meets. Purpose, safety and a sibling exclusion are well covered, but parameter behavior and any indication of paginating/filtering beyond the default 'open' mode are absent.

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 description coverage is 0% and neither parameter is explained. The description's 'open calls' vaguely gestures at the mode default, but it omits that mode accepts open/closed/all and says nothing about the limit parameter, its default of 20, or its maximum of 50. For a two-parameter tool with zero schema documentation, this leaves the caller guessing.

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?

States a clear verb and resource ('List the keeper's open calls in the A2A area') and gives concrete examples of what a call is (paper topic, service discussion, feedback). It also excludes a neighboring category ('not source-review tasks'), which helps separate it from the task-oriented siblings. It does not name a specific sibling tool, and the word 'open' undersells the mode enum, which allows closed and all.

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 'these are not source-review tasks' exclusion provides real routing signal away from the task tools. However, it never states when to prefer this over the many other A2A siblings such as cairn_a2a_mine, cairn_a2a_call or cairn_a2a_tasks, so the guidance remains implied rather than explicit.

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