Registry Lag — how fast MCP directories reflect a new server

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

With no annotations, the description carries the burden of behavioral disclosure. It discloses that the tool performs a live directory check and measures reflection lag, which is useful. However, it does not mention potential rate limits, network dependency, failure behavior, or whether the check is cached.

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?

One sentence, front-loaded with the action and resource, and the lag concept is included without extra fluff. Every word 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?

For a single-parameter lookup tool, the description is mostly complete, but the lack of annotations and output schema means the agent does not know what the return value looks like or what 'lag' means in concrete terms. The sibling get_report is not referenced, so routing context is missing.

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 100%, so the schema already documents the single 'name' parameter. The description adds the notion of a 'server name fragment' but does not add format details beyond the schema's 3-64 char constraint. Baseline 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 states a specific verb ('check') and resource ('whether an MCP server name is listed in public MCP directories right now'), and adds the distinctive 'reflection lag' concept. It is clear enough to distinguish from the sibling get_report, though it does not explicitly name the sibling or contrast itself.

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 implies a real-time lookup use case ('right now') and the lag measurement, but it does not explicitly say when to use this tool versus get_report or when not to use it. The context is inferable but not stated.

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

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

With no annotations, the description carries the behavioral disclosure burden, but it only describes output content. It hints at a running state ('so far') without explaining whether the operation is read-only, what data source it reads, or how it behaves.

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 a single front-loaded sentence with no filler, which is appropriately concise for a zero-parameter tool. It sacrifices an explicit action for brevity, but every word contributes meaning.

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 simplicity and absence of parameters, the description is minimally viable: it tells an agent what data the report contains and names no arguments to supply. Clear gaps remain around output shape, when to call it relative to check_directory_lag, and behavioral guarantees.

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 zero parameters, so there are no parameter semantics for the description to add. Per the baseline for no-parameter tools, this is adequate.

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 names a specific resource—names checked so far—and lists the report fields (run counts, first/last seen timestamps), so the tool's purpose is recognizable. It lacks an explicit verb such as 'returns' or 'lists' and does not mention the sibling tool, so it does not fully differentiate itself.

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?

There is no statement about when to call get_report versus check_directory_lag, no prerequisites, and no indication of whether this tool performs a check or simply reports on one already run. The description is not misleading, but it offers no usage guidance.

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