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

Annotations already declare readOnlyHint=true and openWorldHint=false, and the description goes well beyond that with a genuine cost model: promoted columns are cheap over any window, attr./resource. keys cost ~10x and are only accepted over windows of 31 days or less. That operational context is exactly the behavioral detail an agent needs and cannot get from 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?

Front-loaded with the core instruction, then the grammar/cost model, then per-parameter notes and examples. It is longer than strictly necessary and the grammar explanation is a touch expansive, but nearly every line earns its place.

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?

An output schema exists, so return values need no explanation. For a zero-required-parameter, read-only discovery tool, the description covers purpose, sequencing, cost, and every parameter including worked examples.

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 coverage is 0%, so the description carries the full burden and does so for all four parameters: workspace (accepts id, name, or org/workspace, with default), field (both spellings), prefix (with an example), and hours (default 24). Worked JSON examples reinforce each parameter's intent.

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 specific verb and resource: describing the filter grammar for traces and spans. It is clearly distinguished from the sibling list_agent_traces and list_spans, which it positions itself as a prerequisite to.

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?

Explicitly says to read this before composing `filters` for list_agent_traces or list_spans, and warns that a guessed key is a rejected call. The cost model gives ordered guidance ('narrow with a column first, then add one'), leaving little to inference.

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